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Great for basics and functions

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Horizontal gene transfer (HGT) is the movement of genetic information between organisms, a process that includes the spread of antibiotic resistance genes among bacteria (except for those from parent to offspring), fueling pathogen evolution.

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Homework / Practice #2

1) Read through page 1-39 daily (flag/highlight if unknown)

2) Develop a study plan to study unknown words.

3) Practice the occasional tests, which can be found on the subsequent pages 40-200+.

3) Choose 1 organism from (starter pack p. 7) and describe either of the following

(a) the function and life cycle of the organism,

(b) Bonus: treatments and vaccines for diseases caused by the organism

(c) Bonus: describe the structure and function of specialized organelles in bacteria and eukaryotic microbes (see 3.a.ii.5)

(d) Bonus: describe how the habitat and life strategy of a microbe is related to the structure and function of the microbe

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https://youtu.be/N1bTXBcwIao?si=x8xpPWOptK-ZLS07

accent, but good video

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Rules Section

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Rules Section

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Metabolic Pathways & Energy AP biology 3.4

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Homework / Practice #1 (old)

1) Practice using your binder

2) Study vocabulary words

3) Visual identification

4) Create practice questions

5) Timed practice test

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Rules Section

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https://youtu.be/36ofpuLl878?si=mR79POBNoOkymzvz

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From One Cell to Billions - Colony Forming Units

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https://youtu.be/uIIxNLPUu8g?si=J5BCBMnwwV8_GnSG

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How to Calculate CFU per ml of Bacterial Sample? in 3 Steps || cfu/ml in Microbiology

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https://youtu.be/_Ql1Xn_IBVo?si=2XjEabeKGCTwUZ2W

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https://youtu.be/CfOecDMBrOk?si=1eU_yemnGu4Imb6c

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phases of bacterial growth, lag, log or exponential, stationary, and death phase.

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https://youtu.be/8AhDxAQaDOA?si=Jq2jVC7Ek9kyQkll

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Bacterial Growth Curve & Generation time Calculation

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Rules Section

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https://youtu.be/U66FloGr-s0?si=O3tfpCApoprS5OFo

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Bacterial growth Curve Explained | Phases of Bacterial Growth Curve| Binary Fission |

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https://youtu.be/JpnH_6kqvdw?si=w-N_38DIftGw8Ucl

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Bacterial Growth Curve in 2 minutes|4 Phases of Microbial Growth Curve🦠| Microbiology@biologyexams4u

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https://youtu.be/9cy9VqVUODo?si=JrRy09Aq12jLVY4r

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Bacterial culture media |classification and types of bacterial media | enriched & differential media

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https://youtu.be/EC-U6tv6Wf4?si=VHV9Mk9MdcW7XVC0

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https://youtu.be/Jvo6IGKTvxA?si=vRkHCPww_gv0uidv

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Gram Positive vs. Gram Negative Bacteria

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https://youtu.be/1SITCrgF3yk?si=gRMqWQlpXitipvpT

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https://youtu.be/MI-FkBDamzw?si=xWAF-HHNelQjW6yp

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The Gram Stain (Gram-Positive vs Gram-Negative) and Bacterial Structure | Microbiology 🧫

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https://youtu.be/4kIKySxUYuk?si=aMIw01lx5YW6H2r1

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Virus structure and classification | Cells | MCAT | Khan Academy

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https://youtu.be/nWrX_j_TIpM?si=rXX-_jcY9D01nR9U

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https://youtu.be/PJmtkQpqJxE?si=QyQrvHj8H23T4lML

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Gram positive and gram negative bacteria (Gram Staining procedure explained)

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https://youtu.be/Didrc3wJ3E8?si=FcLrUry_HcVp9sbB

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https://youtu.be/O1TetEto1Is?si=SuMTqj_XlA5vSuPY

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https://youtu.be/HOhF7LauOys?si=70O2v2w8tHrqiR-4

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https://youtu.be/URUJD5NEXC8?si=pSxn5F6q9h3wAdBU

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Biology: Cell Structure I Nucleus Medical Media

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https://youtu.be/b15Hy3jCPDs?si=ia3t8cl8zCSLjc58

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https://youtu.be/PKDj1x3iyP4?si=E27P6rb48GNMJrcm

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How to properly use a compound light microscope

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https://youtu.be/bdxzcoJIlyE?si=WkWPyQTsyhlKOC7_

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Rules Section

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This is a fantastic 1300 page textbook

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Great Intro to Endosymbiotic Theory

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It's good to be friendly with your neighbors, right? Individuals and communities do better if they help each other out. Cooperation isn't just important for humans; without a bit of interaction with neighbors, life as we know it would not exist.

The earliest living neighbors on our planet were all single-celled creatures. Some of the neighboring single-cells joined and began living together as one organism, one inside the other. This partnership was so successful that it led to the evolution of many of the life forms on our planet, including humans.

What is a Cell?

All living things are made up of cells. Even though there are many millions of life forms on earth, all of them are made up of only two basic types of cell: prokaryotes and eukaryotes.

Cells contain DNA. Prokaryotes (pro-carry-oats) are small and simple and have rings of circular DNA floating free inside the cell. Eukaryotes (you-carry-oats) are large and more complex. They have a nucleus, which holds strings of linear DNA within a lipid membrane. All the life forms that you are used to seeing - animals (including humans), plants, and fungi - are made up of eukaryotic cells. The bacteria, which are too small to see without a microscope, are made up of prokaryotic cells.

Prokaryotic cells were some of the earliest life forms on earth. They first appear in the fossil record around 4 billion years ago. Prokaryotes were around for a long, long time before eukaryotic cells appeared around 1.8 billion years ago. This has led us to think that the ancestor of all eukaryotic cells was a prokaryote.

But to get from a prokaryote to a eukaryote, the cell needed to become a lot more complicated. Eukaryotic cells are powered by special organelles, which work a bit like batteries. All eukaryotes have an organelle called the mitochondrion, which makes energy to power the cell. Plant cells have another type of organelle called a plastid. Plastids can harvest energy from sunlight, like a solar battery. Chloroplasts are a type of plastid.

What is Endosymbiotic Theory?

How did the eukaryotes become so complicated? And where did these battery-like organelles come from?

We think we know part of the answer. Eukaryotic cells may have evolved when multiple cells joined together into one. They began to live in what we call symbiotic relationships. The theory that explains how this could have happened is called endosymbiotic theory. An endosymbiont is one organism that lives inside of another one. All eukaryotic cells, like your own, are creatures that are made up of the parts of other creatures.

The mitochondrion and the chloroplast are both organelles that were once free-living cells. They were prokaryotes that ended up inside of other cells (host cells). They may have joined the other cell by being eaten (a process called phagocytosis), or perhaps they were parasites of that host cell.

Rather than being digested by or killing the host cell, the inner cell survived and together they thrived. It's kind of like a landlord and a tenant. The host cell provides a comfortable, safe place to live and the organelle pays rent by making energy that the host cell can use. This happened a long time ago, and over time the organelle and the host cell have evolved together. Now one could not exist without the other. Today they function as a single organism, but we can still find evidence of the free-living past of the organelles if we look closely.

What Evidence Supports Endosymbiotic Theory?

As early as 1883, botanist Andreas Schimper was looking at the plastid organelles of plant cells using a microscope. He watched the plastids divide and noticed something odd. The process looked very similar to the way some free-living bacteria divided.

During the 1950s and 60s, scientists found that both mitochondria and plastids inside plant cells had their own DNA. It was different from the rest of the plant cell DNA. When scientists looked closer at the genes in the mitochondrial and plastid DNA, they found that the genes were more like those from prokaryotes. This tells us that organelles are more closely related to prokaryotes.

The green chloroplasts in this cell are now a critical part of plant cells, but they evolved from an entirely different organism than the plant cell. The chloroplast is thought to have evolved from a cyanobacterial cell that managed to survive the cell's defenses.

We know that multiple membranes surround the organelles too. If we look at the molecules of those membranes, they look like the membranes that surround modern day free-living prokaryotes.

So, organelles have their own DNA, and their genes are very similar to the genes of modern-day prokaryotes. They have membranes that look like those of prokaryotes, and they also seem to divide and replicate in similar ways. If a eukaryotic cell loses an organelle, it cannot remake it. Each eukaryote cell has to inherit at least one copy of an organelle from its parent cell if it is to live. That means that the genetic information needed to make the organelles is not found in the DNA of the eukaryotic cell. All of this evidence supports the theory that the organelles came from outside the eukaryotic cell. We think it tells us that they were once free-living prokaryotes.

A scientist named Lynn Margulis put all of this information together and published it in 1967. Her paper is called "On the origin of mitosing cells". Mitosing cells are eukaryotes. Today scientists know her paper is very important, but it took many years before they accepted her theory.

But our story of the evolution of eukaryotic cells is far from complete. We haven't talked at all about the other structures that we can find in eukaryotic cells but not in prokaryotic cells, and how they evolved. These include the nucleus, Golgi apparatus, endoplasmic reticulum, lysosomes, and cytoskeleton.

Where did they come from? The truth is we are still not sure. They could have evolved over time within the eukaryotic cells. Or, they could also be the result of other ancient endosymbiotic events. How they evolved is a problem that still needs to be solved.

Additional images via Wikimedia Commons. Filamentous cyanobacteria via Sally Warring.

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Everything that is alive is made of cells, but there are really only two main types of cells. Learn how these cell types became different and why they are so important to life.Also in: Español | Italiano | 简体中文

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Rules Section

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https://en.wikipedia.org/wiki/Microbial_metabolism

Really good resource to get an overview

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Microbial metabolism is the means by which a microbe obtains the energy and nutrients (e.g. carbon) it needs to live and reproduce. Microbes use many different types of metabolic strategies and species can often be differentiated from each other based on metabolic characteristics. The specific metabolic properties of a microbe are the major factors in determining that microbe’s ecological niche, and often allow for that microbe to be useful in industrial processes or responsible for biogeochemical cycles.

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This is a great resource that covers a few of the concepts under the culture and growth section.

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Immunology & Microbiology from Technology Networks

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Bacteria are an essential part of the ecosystem. They are crucial to our health and the environment, have an important role in food production and provide bioengineers with tools to harness their properties and manufacture compounds. However, they can also be harmful, causing damage and disease. The ability to grow these microbes is therefore an essential step in being able to utilize their power, identify harmful culprits and advance our understanding and capabilities. In this article, we consider what bacterial culture is, factors affecting culture conditions, common problems and some of the numerous applications.

What is bacterial culture?

Bacterial culture is a method that allows the multiplication of bacterial cells in or on a culture medium under controlled laboratory conditions. The exact conditions required for optimal replication will depend on the target bacterial species.

What's the difference between aerobic culture vs anaerobic culture?

Most bacteria can grow to some extent in the presence of oxygen, known as aerobic culture. But for optimal growth, the conditions should be adjusted to suit the target bacterium. Species found in atmospheric conditions, such as on the skin surface or in the upper respiratory tract, will typically grow well in the presence of oxygen. Species that are naturally found in low oxygen environments, such as in deep wounds or abscesses or the deep ocean, will typically grow best in the absence of oxygen - anaerobic culture. Some cannot grow in the presence of oxygen at all, and these are called obligate anaerobes. Examples include Fusobacterium and Bacteroides. Likewise, those that cannot grow in the absence of oxygen are called obligate aerobes. Examples for the purposes of culture include the Gram negative Pseudomonas aeruginosaand Mycobacterium tuberculosis, the causative agent of tuberculosis. However, studies suggest that both can undertake anaerobic respiration in certain circumstances. Bacteria that can grow in either aerobic or anerobic conditions, switching from aerobic respiration to fermentation or anaerobic respiration if oxygen is absent, are called facultative anaerobes. Examples include the Gram positive staphylococci, Escherichia coli ( E. coli), Salmonella and Listeria spp..

Bacterial culture methods

To be cultured successfully, bacteria require the provision of nutrients in the culture medium. There are many different formulations available to suit the differing nutritional needs of bacterial species. The type of medium you choose will depend on the purpose of the culture. Rich, nutrient or complete media can be helpful when trying to bulk up a pure culture and get the bacterial cells in good condition. Minimal media on the other hand will supply only the bare necessities for survival and can be useful in manipulating which pathways are turned on in the bacterium.

Media may also be classed as defined or undefined. As the names suggests, in a defined media, all the ingredients are known. Undefined media tend to contain complex mixtures of nutrients and chemical species in unknown proportions, such as yeast extract.

Whichever medium is chosen, this may be in liquid form as a broth culture, or agar may be added to set the media and allow bacterial cells to be grown on a solid surface.

Culture in liquid media, also known as a broth culture, gives the bacteria present easy access to the available nutrients compared to static bacterial colonies. Gentle agitation to keep the bacteria dispersed through the medium during incubation can aid this access further. Liquid media will also dilute out waste products as they are formed, distributing them through the culture. Consequently, a greater mass of bacteria may be obtained for an equivalent volume of liquid as opposed to solid media.

You may therefore want to use broth cultures when aiming to bulk up your culture, e.g., when using bacteria to produce a desirable compound, in food production or to extract DNA or plasmids from.

When looking to store bacterial strains long term, they may be grown up in liquid media. Glycerol is then added, which will prevent complete freezing and consequent lysis of the bacterial cells, permitting their storage at -80 ° C. Long-term storage in this manner preserves strains - helpful when collecting strains over a long period of time - prevents the loss of valuable strains and also reduces the risk of mutations that may occur from repeated passaging.

Adding agar to liquid media enables it to be set in petri dishes, as slopes or in plugs for example. Solid media is useful when you wish to select individual colonies from a mixed culture, for example when purifying a diagnostic sample. If you wish to enumerate the number of colony forming units (cfu) within a given volume of liquid sample, plating and incubation on solid media also permits this. Inoculation onto slopes or in stab cultures can also be a convenient method for transporting strains from lab to lab without the danger of spillage of potentially infectious materials.

Selective and differential media

Selective media are also available that promote or suppress the growth of certain species, groups of species or strains with particular properties. This may be based on a strain's ability to utilize specific nutrients, produce certain byproducts or resistance to certain antibiotics. Selection may be used in both broth and solid media.

The ability of the strain to grow or not may be indicated by color changes in differential media and is often used to identify bacterial species or subtypes. For example, with analytical profile index (API) test strips, bacteria are cultured with a range of substrates, producing differing color change patterns based on their metabolism, thus enabling identification.

Where strains are hemolytic, growth on blood agar enables the type of hemolysis to be evaluated, helping to identify the species present (Figure 1).

Blood agar culture showing alpha (left), beta (center) and gamma (right) hemolysis. Figure 1: Credit: Mibilehre, reproduced under the Creative Commons Attribution-Share Alike 4.0 International license.

Addition of antibiotics to liquid media will prevent the growth of non-resistant strains. This may be helpful when culturing an engineered strain into which an antibiotic resistance gene has been added as a marker. Growth of contaminating species or colonies in which the engineering has been unsuccessful will therefore be selected against.

Antibiotics may be added to solid media during preparation, fulfilling a similar role to that in liquid media. Alternatively, antibiotic-infused disks may be placed onto solid media onto which a stain of interest has been inoculated. Where the strain is sensitive to the antibiotic, a clear zone of no growth will then be visible around the disc as the bacterial lawn grows, enabling, for example, a suitable antibiotic to be chosen for treatment of an infection (Figure 2).

Antibiotic resistance tests; the bacteria in the culture on the left are sensitive to the antibiotics contained in the white paper discs. The bacteria on the right are resistant to most of the antibiotics. Credit: Dr Graham Beards, reproduced under the Creative Commons Attribution-Share Alike 4.0 International license.

As well as the oxygen conditions and nutrient requirements already discussed, the temperature and humidity at which different species will grow optimally varies too, reflecting their natural habitat. Species typically found deep in the body, such as the gut or lower respiratory tract, are likely to grow best at 37 ° C - body temperature. Conversely, species found, for example, in soil are likely to require cooler temperatures. When performing genetic manipulations on bacteria, temperature can be used as a switch to control the integration of temperature-sensitive plasmids and consequently promote the desired outcome.

What's a bacterial growth curve?

While rates of division will vary between bacterial species, they will normally follow the same general growth pattern in broth culture. The number of bacterial cells in a culture can be estimated by various means including plating and colony counting or by measuring the turbidity of the culture with UV-visible spectroscopy. When this is plotted (typically on a logarithmic scale) against time, it is known as a growth curve, as depicted in Figure 3.

Example of a bacterial growth curve showing the 1) lag phase, 2) exponential/log phase, 3) stationary phase and 4) death phase. - Bacteria are adjusting to their new growth conditions. The length of this phase will depend on how similar these are to their previous conditions and the condition of the cells. The bacteria may need to repair themselves, produce enzymes and RNA for replication or synthesize molecules that are lacking in their surroundings. - Once the cells have adjusted to their conditions and have the molecules they require, cell division begins in earnest. This follows a predictable doubling pattern, the duration of which will depend on how well suited the conditions are to the bacterial species. Rapid growth, and consequently a steep slope, will occur where conditions are close to optimal. This is the point at which the bacterial cells are healthiest and so typically the phase from which cells are utilized for other experiments. - Nutrients become exhausted, waste products build up and space may run short, slowing further division such that the number of new cells produced equals the number dying. This is seen as a flattening out of the growth curve. New bacterial cells undergo physiological changes in an attempt to adapt to starvation conditions. For spore-producing species, sporulation may also begin. - As conditions no longer favor growth, a steady deterioration in the condition of the cells present is observed leading to a decline in the growth curve. Non-viable cells may still contribute to turbidity measures where they are used to estimate cell numbers, keeping values higher than the number of truly viable cells. Usually, some cells will always remain viable as they mutate or enter a dormant state to survive.

Exponential or log phase
Stationary phase
Death or decline phase

A pure culture is one that only contains the bacterial species you wish to grow. The ease with which this can be achieved is likely to depend very much on the source of your sample, the abundance of the target species compared to other species and the target species itself. If your source is another pure culture or a strain that has been isolated and stored in the freezer, then the culture may already be pure. If, however, the source is a clinical or environmental sample, there are likely to be many other bacterial species and potentially fungi present too that will also grow happily in your culture conditions. Selective media and restricted growth conditions (e.g., aerobic vs anerobic culture) can help to eliminate non-target species and narrow the field. Streaking the sample onto solid media rather than into broth culture will allow visual identification of colonies of interest from the general background. It may be necessary to pick and re-streak bacterial colonies of interest onto fresh agar plates a few times before a pure culture can be obtained. Once this is achieved, they may then be grown in liquid culture if desired. If the target species is present only in low numbers, it may be necessary to streak multiple plates from the original sample in order to isolate them. Some species grow more rapidly and vigorously than others, so this too is a factor to consider.

It may not always be necessary to obtain a pure culture depending on the purpose of your experiment. If it is possible to identify the target species among a background of others and this is sufficient for your purpose, then obtaining a pure culture may not be required. However, if you wish, for example, to perform further targeted assays or the bacteria are being cultured for production or food purposes, then obtaining and maintaining a pure culture may be essential.

- Contamination of bacterial cultures can be very problematic, particularly if it goes undetected. At best, it can mean the need to reisolate a pure culture, but at worst could lead to illness and very costly remedial work if it were to occur in a food or production setting. Culture contamination can come from many sources, right from the original sample itself through the process of culturing and even storage. Good Contamination aseptic technique can help to avoid contamination of bacterial cultures.

- Some bacterial species grow easily and vigorously. When attempting to isolate a species from a mixed sample, these vigorous species may overgrow and mask the presence of slower-growing target species. Using selective media and optimal growth conditions for your target species (if known) can help to mitigate this. Try to culture the sample as soon as possible after it has been taken to ensure it is as representative as possible.Overgrowth of some species

- In a diagnostic setting, it is important to know if antibiotic treatment has been administered prior to sampling. If this is the case, failure to culture a particular species may not indicate that it was not the cause of the infection.Antibiotic treatment prior to sampling

- The use of Incorrect growth conditions inappropriate or suboptimal growth conditions may impede or completely prevent the growth of your target strain. Be sure to double check growth requirements or if using antibiotic selection ensure the correct antibiotic has been chosen for the resistance gene present.

Non-culturable and slow-growing organisms - Some bacterial species, even now, cannot be grown in the lab. Others, such as mycobacteria, are very slow growing and can take months to culture successfully, which is particularly problematic when trying to diagnose infections.

Applications of bacterial culture

There are many reasons why it may be necessary or desirable to culture bacterial cells. Here, we consider some of the common purposes.

Despite the length of time it can take to isolate and identify bacterial species from a sample, bacterial culture remains an important diagnostic tool. While PCR may rapidly identify the presence of a specific pathogen, isolating the culprit will confirm that it is alive, alerting analysts to potential transmission risks and informing treatment. It also means the bacterial strain can be interrogated further for information like antibiotic sensitivity, directing treatment choices. Strains may also be stored down for future reference, for example for disease monitoring purposes.

It may be desirable to manipulate the genome of bacterial strains for a number of reasons; trying to understand the basic biology, to attenuate it when creating vaccine strains, to overproduce proteins and to create a reference strain with a detectable marker to name just a few. Whether mutating, deleting or inserting genetic material, there is a fundamental need to culture the strain of interest before, during and after the genetic engineering process.

Epidemiological study

Culturing and characterizing bacterial strains can be vital for epidemiological studies. This enables scientists to study how bacterial populations change over time - which can inform therapeutic, vaccine and diagnostic design and updates - and study transmission events which can in turn inform things like public health policy and advice. The Gonococcal Isolate Surveillance Project (GISP) is one such project that monitors strains for antibiotic resistance, helping to inform drug therapy recommendations. The Centers for Disease Control and Prevention (CDC) also runs the Active Bacterial Core surveillance (ABCs) system, providing laboratory- and population-based surveillance of invasive bacterial pathogens of public health importance.

Scale up to enable omics studies

While sequencing of DNA and RNA can be performed with tiny amounts of genetic material, even on the single-cell level, for many studies, next-generation sequencing (NGS) is still performed on material from many bacterial cells and as such, the bacteria often need to be cultured prior to DNA or RNA extraction. If you are interested in a specific strain (unlike microbiome studies which will contain a mix) then this will likely be derived from a pure culture.

Develop vaccines and therapeutics

In order to fight a bacterial pathogen, you typically need to be able to culture that pathogen too. During the development of vaccines, it may be necessary to culture strains to understand their genomes, amplify their genes or manipulate them. Equally, in order to test out candidate vaccines or therapies, it is often necessary to perform challenge experiments in which individuals are challenged with the pathogen to see if the therapy is effective. To do this, the bacterial strain is normally grown and, in a defined challenge model, enumerated to control and determine the dose subjects receive.

Food and beverage production

Bacteria are an important part of the production of many foods and are broadly split into probiotics and starter cultures.

Probiotics are generally cultured for their benefit to human health, often through our gut microbiome. While probiotics may contain many different bacterial species, Lactobacillus and Bifidobacterium are common choices for culture.

Starter cultures on the other hand are typically used as part of a food production process, to develop flavor, texture, nutritional value or improve preservation. Examples include sourdough breads, salami, pepperoni and dried ham. Lactic acid bacteria (LAB) are commonly found among starter cultures. Some foods and drinks could however, arguably sit in both camps, such as yogurt and the increasingly popular kimchi and kombucha where products are consumed for their flavor as well as their probiotic benefits.

Regardless of the purpose a culture is intended for, maintaining a healthy, contaminant-free culture is vital for optimal production and consumer safety.

Detecting food contaminants

While some bacteria may be desirable in food production, they may also be present as a contaminant and have the potential to cause serious foodborne illnesses. Common causes include Salmonella sp., Listeria monocytogenes, Campylobacter jejuni and E. coli. It is therefore important that analysts are able to culture any potentially hazardous bacteria from food samples, even if they are present in low numbers.

References
1. Garrett WS, Onderdonk AB. 249 - Bacteroides, Prevotella, Porphyromonas, and Fusobacterium Species (and other medically important anaerobic Gram negative bacilli). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases (Eighth Edition). W.B. Saunders; 2015:2773-2780. doi: 10.1016/B978-1-4557-4801-3.00249-6

4. Harris L, Foster S, Richards R. An introduction to Staphylococcus aureus, and techniques for identifying and quantifying S. aureus adhesins in relation to adhesion to biomaterials: review. eCM. 2002;4:39-60. doi: 10.22203/eCM.v004a04

8. Bonnet M, Lagier JC, Raoult D, Khelaifia S. Bacterial culture through selective and non-selective conditions: the evolution of culture media in clinical microbiology. New Microbes New Infect. 2020;34:100622. doi: 10.1016/j.nmni.2019.100622

9. Maier RM. Chapter 3: Bacterial growth. In: Maier RM, Pepper IL, Gerba CP Environmental Microbiology. Academic Press. 2000: 37-54. ISBN: 978-0-12-497570-5

10. Bodor A, Bounedjoum N, Vincze GE et al. Challenges of unculturable bacteria: environmental perspectives. Rev Environ Sci Biotechnol 19, 1-22 (2020). doi: 10.1007/s11157-020-09522-4

11. Pfyffer GE, Wittwer F. Incubation time of mycobacterial cultures: How long is long enough to issue a final negative report to the clinician? J Clin Microbiol. 2012;50(12):4188-4189. doi: 10.1128/JCM.02283-12

12. Giuliano C, Patel CR, Kale-Pradhan PB. A guide to bacterial culture identification and results interpretation. P T. 2019;44(4):192-200. PMC 6428495

13. Fels U, Gevaert K, Van Damme P. Bacterial genetic engineering by means of recombineering for reverse genetics. Front. Microbiol. 2020;11:2161. doi: 10.3389/fmicb.2020.548410

14. Parkhill J, Wren BW. Bacterial epidemiology and biology - lessons from genome sequencing. Genome Biol. 2011;12(10):230. doi: 10.1186/gb-2011-12-10-230

15. Gautam SS, KC R, Leong KW, Mac Aogáin M, O'Toole RF. A step-by-step beginner's protocol for whole genome sequencing of human bacterial pathogens. J Biol Methods. 2019;6(1):e110. doi: 10.14440/jbm.2019.276

16. Giesker K, Hensel M. Bacterial vaccines. In: Reference Module in Biomedical Sciences. Elsevier; 2014. doi: 10.1016/B978-0-12-801238-3.00141-0

18. Bazireh H, Shariati P, Azimzadeh Jamalkandi S, Ahmadi A, Boroumand MA. Isolation of novel probiotic Lactobacillus and Enterococcus strains from human salivary and fecal sources. Front Microbiol. 2020;11:3064. doi: 10.3389/fmicb.2020.597946

19. Yoon JY, Kim D, Kim EB, Lee SK, Lee M, Jang A. Quality and lactic acid bacteria diversity of pork salami containing kimchi powder. Korean J Food Sci Anim Resour. 2018;38(5):912-926. doi: 10.5851/kosfa.2018.e24

20. Song HS, Whon TW, Kim J, et al. Microbial niches in raw ingredients determine microbial community assembly during kimchi fermentation. Food Chem. 2020;318:126481. doi: 10.1016/j.foodchem.2020.126481

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The ability to grow microbes is an essential step in being able to utilize their power, identify harmful culprits and advance our understanding and capabilities. In this article, we consider what bacterial culture is, factors affecting culture conditions, common problems and some of the numerous applications.

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Copy of Jordan Zuniga & Yvette Norez - Science Olympiad Event Syllabus: Plan of Study

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Practice Tests -

https://scioly.org/tests/

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To prepare effectively for the Science Olympiad, here’s a step-by-step approach that might help you:

1. Understand the Event Rules and Structure

Review the official rules for your specific events. Each event has its own focus, whether it's biology, chemistry, physics, or engineering, so it's crucial to know what topics will be covered.

2. Organize a Study Schedule

Break down the topics for each event you're participating in and create a study schedule. Prioritize the areas you're less familiar with but ensure you're also reviewing your stronger areas.

3. Gather Study Materials

Use textbooks, online resources, and Science Olympiad study guides specific to your events. Websites like Scioly.org have practice tests and other resources.

If your event involves experiments or building, practice those hands-on skills regularly.

4. Practice with Past Exams

Find and work on past Science Olympiad exams to get familiar with the format and types of questions.

Time yourself to simulate real competition conditions.

5. Collaborate with Teammates

Science Olympiad is a team-based event, so working with your teammates to study, run practice tests, and give feedback can improve your understanding.

If there’s a team coach, seek their guidance on areas that need improvement.

6. Focus on Speed and Accuracy

Time management is crucial during the competition. Practice answering questions quickly while maintaining accuracy.

7. Prepare for Build Events

If you're in build events, make sure you practice constructing your devices and testing them under different conditions. Ensure you are familiar with the required materials and constraints.

Practice troubleshooting common problems with your devices.

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(4) Virus Structure https://micro.magnet.fsu.edu/cells/virus.html

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Molecular Expressions Cell Biology: Virus Structure

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Viruses are not organisms in the strict sense of the word, but reproduce and have an intimate, if parasitic, relationship with all living organisms. Explore the structure of a virus with our three-dimensional graphics.

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(3) Bacterial Cell Shapes

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Table of Contents

Download Complete Chapter Notes of Biological Classification
Download Now

Bacteria is a prokaryotic, unicellular organism. Bacteria are found everywhere, they are the most abundant living organisms. They can thrive in extreme conditions like hot springs, snow, deep ocean, where it is difficult for other organisms to live.

Salient features of bacteria are the following:

Unicellular prokaryotic cell

Present in different shape, size and arrangement

The cell lack nucleus and membrane-bound cell organelles

Bacterial DNA is found in the cytoplasm and not packaged to form chromatin as in eukaryotic cell

Bacteria cell is 10 times smaller than the human cell

The diameter of a bacteria cell is ~1µm (10⁻⁶ m)

The outer covering of a bacteria cell is the cell wall, which is rigid and provides structural integrity

The bacteria cell wall is made up of peptidoglycan or murein

Different shapes of bacteria cell are the characteristic feature of a bacteria species

Bacteria cells may contain external appendages like cilia, flagella, etc.

Bacteria can be photoautotrophs, chemoautotrophs or parasites

Morphology of a Bacteria Cell

Morphology or shape of a bacteria cell is the most distinguished property of a bacteria. It is the characteristic property of a particular species.

Morphology of bacteria cell not only tells the shape but also decides its pathogenicity. Morphological traits of a bacteria cell are an important factor in its adaptability and evolution. There are many features like motility, mode of nutrition, that are affected by the shape of bacteria.

The bacterial cell wall is made up of peptidoglycan (murein), which is a polymer of sugars, alternating N-acetylglucosamine (NAG) linked to N-acetylmuramic acid (NAM) and amino acids peptide chain. Change in the configuration of the polymer and its thickness is responsible for the varied morphology and shape of a bacteria cell.

Read more: Motile and Non-motile Bacteria Examples

Size of Bacteria

The size of bacteria can be averaged to 2 micrometres with a diameter of 0.5 micrometres. Bacteria are known to display a wide variety of size and shapes. They are about one-tenth the size of a eukaryotic cell.

Different shapes of bacteria

Different shapes of bacteria are used to categorise bacteria. Different shapes of a bacterial cell are:
1. Spherical- Cocci:

Cocci can be single or multiple in a group of 2, 4, 8, etc. Cocci bacteria can be round, oval or elongated or bean-shaped.

The cell wall of coccus shaped bacteria may be gram-positive with thick peptidoglycan layer, or gram-negative with the thin peptidoglycan cell wall

The cells do not separate after cell division. The plane of cell division changes the shape of the bacteria

According to the arrangement of cells, cocci bacteriaare subdivided into various subtypes:

1. Monococcus: bacteria exist as a single spherical cell

2. Diplococcus: Cells are arranged in pairs after cell division.Examples of diplococcus bacteria are:Gram-negative bacteria- Neisseria spp, Moraxella catarrhalisGram-positive bacteria- Streptococcus pneumoniae, Enterococcus spp, etc.

3. Streptococcus: the cocci are joined in a plane and arranged in a chain pattern. These are non-motile, aerobic and gram-positive bacteria that cause many diseases.Examples of streptococci are Streptococcus mutans, Streptococcus pyogenes, Streptococcus bovis, Streptococcus agalactiae, etc.

4. Tetrads: Tetrads are arranged in a group of 4 cells. The cell division occurs in two different planes.Examples of tetrads cocci bacteria are Micrococcus spp, Pediococcus, etc.

5. Staphylococcus: Cells are arranged in an irregular cluster, which looks like grapes. This is due to the division in three planes.Examples of staphylococcus are staphylococcus aureus, Staphylococcus haemolyticus, etc.

6. Sarcinae: Sarcinae bacteria are anaerobic gram-positive bacteria. They occur as a group of 8 cells. It is found in the family Clostridiaceae. It is found in the large intestine and skin.Examples of sarcinae are: Clostridium maximum, Sarcina auranatica, Sarcina ventriculi, Clostridium maximum, Microcioccus luteus, etc.

2. Rod-shaped- Bacilli:

These are rod shaped bacteria. They also occur singly or as multiple cells attached after the cell division.

Bacilliform bacteria are found in many different taxonomic groups of bacteria

Bacilliform bacteria can be gram-positive, e.g. Actinomyces, Clostridium, Bacillus or gram-negative bacteria, e.g. Escherichia, Klebsiella, Salmonella, Streptobacillus, etc.

Bacteria of genus Bacillus are gram-positive, rod shaped bacteria

They are obligate aerobe or facultative anaerobic bacteria

They can form endospores and live for years as dormant and resistant to heat, radiation and disinfectants

They can survive extreme heat and temp as high as 420 ℃

They are the most abundant bacteria and found everywhere

Mostly non-parasitic, free-living species

Two parasitic and pathogenic bacillus species are Bacillus anthracis causing anthrax and Bacillus cereus, which causes food poisoning

Based on the arrangement of rod shaped cells, bacilli are classified into various types:

1. Bacillus: Single unattached cell, that looks like a rod.Examples are Bacillus cereus, Salmonella enterica, etc.

2. Diplobacilli: Two rods are attached to each other and found in pairs after cell division.Examples are Moraxella bovis, Klebsiella rhinoscleromatis, etc.

3. Streptobacilli: Due to cell division in one plane, bacilli are arranged in a chain. Genus Streptobacillus contains gram-negative, aerobic or facultative anaerobic bacteria.Examples are Streptobacillus moniliformis, Streptobacillus felis, etc.

4. Coccobacilli: These are short compared to other bacilli and oval in shape, they appear like a coccus.Examples are Chlamydia trachomatis, Haemophilus influenzae, Gardnerella vaginalis, etc.

5. Palisades: The bacilli after cell division bend and therefore arranged in a palisade, fence-like structure. Example: Corynebacterium diptheria

3. Spiral bacteria:

These bacteria are spiral or helical in shape.
Based on the thickness, flexibility and motility of the cell, they are further divided into two types:

1. Spirillum: These are gram-negative, rigid bacteria having external flagella.Examples are Spirillum, Campylobacter jejuni, Helicobacter pylori, etc.

2. Spirochete: These bacteria are spiral, thin and flexible. They have internal periplasmic flagella. These are pathogenic species that cause various serious diseases.Examples are Leptospira, Treponema pallidum, etc.

4. Comma shaped- Vibrio:

These are curved and appear like a comma.

These are mostly gram-negative bacteria

They are known to cause various foodborne diseases

Vibrio sp are facultative anaerobes and have 2 chromosomes which replicate independently

Examples are Vibrio cholerae, Vibrio parahaemolyticus, etc.

Other than the main 4 shapes, the bacterial cell possess various different morphology namely

Filamentous: have a long filamentous structure. Example: Candidatus savagella

Star-shaped: resemble a star. Example: Stella humosa, Stella vacuolata

Rectangular: these are box or rectangular shaped. Example: halophilic bacteria such as Haloarcula vallismortis

Pleomorphic: these have ability to change their shape and size due to various external factors like pressure, environmental stress, etc. Example: Mycoplasma pneumonia, Mycoplasma genitalium

Appendaged: they are also known as budding bacteria. They can be non-motile or motile with flagella. Example: Hypomicrobium, Rhodomicrobium

Trichome: trichomes are a chain of vegetative cell. This is often covered with slimy sheath as in cyanobacteria. Example: Thiothrix nivea

Lobed: these have a lobed structure and mostly found in hot and volcanic springs. They are flagellated and have an irregular shape. They are acidophiles and thermophiles. Example: Sulfolobus acidocaldarius, Sulfolobus solfataricus

Fusiform: these are spindle-shaped, bulged in the middle and the end is tapered. Example: Fusobacterium necrophorum

Stalked: a stalk develops at one end of bacteria due to asymmetrical cell division. Example: Caulobacter crescentus

Sheathed: bacteria cell is covered with sheath. They are found in water. Example: Leptothrix, Clonothrix

This was about the morphology of bacteria. Learn similar concepts from perspective only at BYJU'S.
Also Check:
Recommended Video:

Frequently Asked Questions

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Morphology, Different shapes of bacterial cell

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Bacteria are classified on the basis of their shapes. The main four shapes are spherical (coccus), rod shaped (bacillus), comma-shaped (vibrio), spiral (spirilla)

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(1) Bacteria Cell Structure

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Molecular Expressions Cell Biology: Bacteria Cell Structure

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One of the earliest prokaryotic cells to have evolved, bacteria have been around for at least 3.5 billion years and live in just about every environment imaginable. Explore the structure of a bacteria cell with our three-dimensional graphics.

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(2) Gram Stain Test

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Overview

What is a Gram stain?

A Gram stain is a laboratory test that checks for bacteria at the site of a suspected infection or in certain bodily fluids. A medical laboratory scientist processes the Gram stain, which gives relatively quick results, so healthcare providers can know if bacteria are present, and, if so, the general type(s). This can help guide further identification tests and treatment options.

Bacteria are a large group of one-celled organisms. They can live in different places in your body and on your skin. While some types of bacteria are harmless or even beneficial, others can cause infections and disease. A Gram stain helps diagnose harmful bacteria.

Under a Gram stain, different kinds of bacteria change one of two sets of colors (pink to red or purple to blue) under a special series of stains and are categorized as "gram-negative" or "gram-positive," accordingly. Gram staining works by differentiating bacteria by the chemical and physical properties of their cell walls.

However, not all forms of bacteria can be tested using the Gram stain method, and Gram stains don't usually provide a diagnosis alone. Instead, they help to broadly determine the type of bacteria.

Gram staining is an essential staining technique in microbiology that scientists have used for hundreds of years. It's named after Danish bacteriologist Hans Christian Gram, who first introduced it in 1882, mainly to identify organisms causing pneumonia.

What are gram-positive and gram-negative bacteria?

If bacteria are present on a Gram stain slide, a medical laboratory scientist classifies them as gram-negative or gram-positive based on which color they turn under a series of stains. There are also gram-variable bacteria, which means they stain irregularly, and there's a mix of pink- and purple-colored bacteria.

It's important to note that gram-negative doesn't mean there are no bacteria, and "positive" and "negative" don't mean "good" and "bad" in this case.

Gram-positive organisms

Gram-positive bacteria have cell walls that contain thick layers of peptidoglycan, a substance that forms the cell walls of many bacteria. The peptidoglycan forms about 90% of the cell wall in gram-positive bacteria. This causes them to appear blue to purple under a Gram stain.

Gram-positive organisms include:

Gram-negative organisms

Gram-negative bacteria have cell walls with thin layers of peptidoglycan (10% of the cell wall) and high lipid (fatty acid) content. This causes them to appear red to pink under a Gram stain.

Gram-negative organisms include:

What's the difference between a Gram stain and a bacteria culture?

Healthcare providers use both Gram stains and bacteria cultures if they suspect you have a bacterial infection. However, these tests provide different information.

Providers usually request bacteria culture tests alongside Gram stain tests. In a bacteria culture test, a medical laboratory scientist takes cells from the sample that's also for the Gram stain and puts it in a special environment to encourage cell growth. Results are often available within a few days, but some types of bacteria grow slowly, which may take several days or longer. Once the cells have multiplied and grown enough, a medical laboratory scientist examines the cultured bacteria to determine their exact identity.

A Gram stain involves applying a stain to a sample in glass microscope slides and looking at it under a microscope to determine if bacteria are present at all. If bacteria are present, the medical laboratory scientists can see if they're gram-negative or gram-positive based on if the bacteria appear pink to red or purple to blue under the stain. Different types of bacteria are either gram-negative or gram-positive.

While Gram stains provide quicker results than bacteria cultures, in most cases, a Gram stain can't diagnose the type of bacterium, unlike a bacteria culture. However, Gram stains can help point healthcare providers in the right direction for prescribing treatment.

What conditions do Gram stains help diagnose?

Healthcare providers order Gram stains to help diagnose and treat certain bacterial infections, such as urinary tract infections (UTIs) and bacterial pneumonia. Providers may not always request a Gram stain to help diagnose conditions caused by bacteria. For example, they usually don't Gram stain for food poisoning, but it's possible to do so through a stool (poop) sample.

Common gram-negative bacteria and their associated conditions

Examples of gram-negative bacteria (in italics) and the conditions they can cause include:

: Urinary tract infections (UTIs) and food poisoning.

Legionella pneumoniae: Legionnaires' disease.

Klebsiella: Pneumonia, bloodstream infections, wound or surgical site infections and bacterial meningitis.

Morganella morganii: UTIs, sepsis, pneumonia, wound infections, musculoskeletal infections, central nervous system infections and pericarditis.

Aeromonas: Eye infections, osteomyelitis, bacterial meningitis, respiratory infections following "near drowning" and joint infections.

Common gram-positive bacteria and their associated conditions

Examples of gram-positive bacteria (in italics) and the conditions they can cause include:

When is a Gram test performed?

Healthcare providers typically request a Gram stain along with a bacteria culture when they suspect you have a bacterial, or sometimes fungal, infection. It's one of the most common ways to quickly diagnose bacterial infection in your body.

Who performs a Gram stain test?

Depending on what kind of infection you may have, many types of healthcare providers could collect a sample for a Gram stain test. For example, a gynecologist may collect a swab for a gonorrhea Gram stain test and a pulmonologist may collect a sample of your spit or mucus from your cough to use for a bacterial pneumonia Gram stain test.

Your provider then puts the sample in a sterile container and sends it to a laboratory for testing. A medical laboratory scientist applies the sample to microscope slides, applies a series of stains and looks at the sample under a microscope. They put together a report and share it with your healthcare provider.

Test Details

How do I prepare for a Gram stain test?

You don't need to do anything special to prepare for a Gram stain test.

How is a Gram stain test performed?

There are three general steps involved in a Gram stain test, including:

Collecting the sample.

Processing the sample.

Examining the sample.

Collecting the Gram stain sample

A Gram stain test involves your healthcare provider collecting a sample from a site of suspected infection. Some of the ways a provider can collect Gram stain test samples include:

Brushing or scraping tissue from the surface of a part of your body.

Collecting fluid or discharge samples from your body.

Using fine-needle aspiration to draw a fluid sample from an area in your body.

Sites collected by a swab with brushing and scraping may include your:

Samples that you can collect directly into a sterile container include:

Areas in your body that may require the use of fine-needle aspiration include:

Synovial fluid in your joints.

Fluid around your heart (pericardial fluid).

Fluid around your lungs (pleural fluid).

Cerebrospinal fluid (CSF) around your spinal cord.

Your provider then puts the sample in a sterile container and sends it to a laboratory for testing.

Gram staining procedure

At the lab, a medical laboratory scientist smears or spreads the sample on glass microscope slides. These slides are known as smears. They then apply a series of stains to the smear to perform a Gram stain.

The Gram staining process includes four basic steps, including:

1. Applying a primary stain (crystal violet).

2. Adding a mordant (Gram's iodine).

3. Rapid decolorization with ethanol, acetone or a mixture of both.

4. Counterstaining with safranin.

Examining the Gram stain

The medical laboratory scientist then categorizes any bacteria that may be present by color and shape during the microscopic evaluation:

Color: Typically, bacteria that are gram-positive appear purple to blue, and bacteria that are Gram-negative appear pink to red.

Shape: The most common shapes include round (cocci) or rod-shaped (bacilli).

The medical laboratory scientist also looks for additional characteristics of the sample by observing the groupings of the bacteria on the slide. Examples include:

Cocci that are present singly, in pairs, in groups of four, in clusters or in chains.

Bacilli that are thick, thin, short, long or have enlarged spores on one end.

If bacteria are present within white blood cells.

The medical laboratory scientist then puts together a report and sends it to your healthcare provider.

What are the risks of a Gram stain test?

There's no risk to having a Gram stain that involves a swab or fluid collection of sputum (spit), urine or stool.

There's very little risk to having blood tests. You may have slight tenderness or a bruise at the site of the blood draw, but this usually resolves quickly.

Possible fine-needle aspiration risks include:

Discomfort or soreness.

Bleeding.

Infection.

Damage to nearby structures.

Results and Follow-Up

What do the results of a Gram stain mean?

Gram stain test results reveal one of two categories: a negative Gram stain or a positive Gram stain. This is not to be confused with gram-negative bacteria or gram-positive bacteria.

Negative Gram stain

If your test result reveals a negative Gram stain or "no organism seen," it usually means that there are too few bacteria present to be able to be seen using the Gram stain method. Bacteria might still be detected by culture if a culture is performed on the specimen.

Positive Gram stain

If your test result reveals a positive Gram stain, it means that bacteria were present in your sample. If your result is positive, it usually includes information about what kind of organism was present on the sample slide, including:

Type of bacteria: Gram-positive or gram-negative.

Shape of bacteria: Round (cocci) or rods (bacilli).

Other bacteria characteristics: Size, relative quantity (number) and/or arrangement of the bacteria, if applicable.

Other cells: Whether there are bacteria present within other cells (intracellular) and if there's a presence of red blood cells or white blood cells.

Fungi: Gram stains can check for the presence of fungi in the form of yeasts or molds. You may need further testing to identify the specific type.

This information, along with signs and symptoms and other clinical findings, will help your healthcare provider determine which treatment may be most effective, sometimes before bacteria culture results are available.

When should I know the results of the test?

Gram stains generally provide quick results. However, Gram stain results are usually considered preliminary, meaning they can't always provide a diagnosis alone. Results of a bacteria culture and/or other tests, such as antigen and antibody testing for particular types of bacteria, might be necessary to confirm a diagnosis.

When should I call my doctor?

If you've been diagnosed with an infection and are having issues with your treatment or your infection isn't improving, contact your healthcare provider.
A note from Cleveland Clinic
Gram stains are a very common and often painless way to determine the presence of a bacterial or fungal infection. While it can be stressful to wait for the results of a diagnostic test, know that your healthcare team is there to support you no matter what the results are. Don't be afraid to ask your healthcare provider questions about your test or results.

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Gram Stain: What It Is, Purpose, Procedure & Results

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A Gram stain is a laboratory test that checks for bacteria at the site of a suspected infection or in certain bodily fluids. A medical laboratory scientist processes the Gram stain, which gives relatively quick results, so healthcare providers can know if bacteria are present, and, if so, the general type(s).

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(3) We need to practice stimating the size of microbes using scale bars.

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(2) Difference Between Light Microscope and Electron Microscope

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(1) Brightfield Microscope: Principle, Parts, Applications

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Insights into Microbial Metabolism - The Tiny Powerhouses (3 Minutes)

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Understanding Cell Division in Bacteria | Introduction to Biology

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Carbon and Energy Source - Metabolism: Microbiology for Nursing School & Health Fields | @LevelUpRN

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This textbook is pretty good. It has decent navigation.

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Part 1 of 3

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Metabolic Diversity (photo-/chemo-, auto-/hetero-, litho-/organo-trophy) | GEO GIRL

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Extremophiles: Microscopic Survivors Living on the Edge

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SCIOLY Microbe Mission Wiki - Not a bad one-stop shop of info.

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Part 2 of 3

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For your Microbe Mission event, here’s a tailored study schedule based on the topics and skills required. Since this event involves both theoretical knowledge and practical lab skills, the study plan will balance both.

Day 1: Microscopy & Structure/Morphology

1 Hour: Microscopy

Review:

Types of microscopes (light, electron, etc.) and their uses.

Microscopy techniques (staining, phase-contrast, fluorescence).

How to calculate magnification and field of view.

Practice:

Set up a microscope and examine prepared slides (if available).

Learn to adjust focus, contrast, and lighting.

30 Minutes: Structure and Morphology

Review:

Cell structure (prokaryotic vs eukaryotic).

Morphological characteristics of bacteria, viruses, fungi, and protozoa (e.g., shapes, arrangements).

Practice:

Label diagrams of microbial structures and understand their functions (flagella, pili, capsules, etc.).

30 Minutes: Lab Skills

Practice:

Measure objects using a microscope. Practice making detailed observations and measurements using different lenses.

Conduct any simple staining techniques available (Gram staining or methylene blue, if possible).

Day 2: Culture and Growth

1 Hour: Microbial Growth

Review:

Conditions for microbial growth (temperature, pH, oxygen requirements).

Growth media (nutrient agar, selective/differential media).

Phases of microbial growth (lag, log, stationary, death phase).

Practice:

Interpret microbial growth curves and analyze factors affecting growth rates.

30 Minutes: Quantitative Reasoning and Calculations

Practice:

Calculate population size from growth curves, doubling times, and dilution factors.

30 Minutes: Lab Skills

Practice:

Learn how to plate bacteria (if access to lab equipment is possible).

Understand sterile techniques to avoid contamination.

Day 3: Metabolism and Applications, Evolution & Ecology

1 Hour: Metabolism and Applications

Review:

Basics of microbial metabolism (aerobic/anaerobic respiration, fermentation).

Microbial applications (biotechnology, fermentation processes, biofuels, antibiotics).

Practice:

Analyze data from experiments involving microbial metabolism (e.g., respiration rates, gas production).

30 Minutes: Evolution & Ecology

Review:

Microbial evolution and genetic diversity (mutations, horizontal gene transfer).

Roles of microbes in ecosystems (nitrogen cycle, symbiosis, decomposition).

30 Minutes: Lab Skills

Practice:

Interpret ecological data from experiments or datasets involving microbial populations.

Practice using data analysis tools or software if applicable to your event.

Day 4: Microbes and Agents List & Lab Practical Prep

1 Hour: Microbes and Agents List

Review:

Go over the major microbes/agents on the list (pathogens, viruses, bacteria).

Understand their characteristics, diseases they cause, and methods of transmission.

30 Minutes: Lab-Practical Simulations

Practice:

Review common lab-practical tasks, such as measuring, using probes, or interpreting experimental data.

Conduct simulated tasks like using pipettes or other lab equipment (if possible).

30 Minutes: Process Skills Focus

Practice:

Focus on interpreting data, making conclusions from experimental setups, and solving quantitative problems.

General Tips:

Rotate Topics: Use each day to rotate through topics so that you cover all aspects by the end of each week.

Mock Exams: Every couple of weeks, simulate a test or lab-practical with various questions and tasks to get comfortable with the competition format.

Group Discussions: Collaborate with teammates, discuss challenging topics, and practice explaining concepts to others.

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Extremophiles Part-2: Survival Strategies of Microbes in Extreme Environmental Conditions

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Lytic and Lysogenic Cycles of Virus Replication

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Part 3 of 3

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Virus Life Cycle | Health | Biology | FuseSchool

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Lytic v. Lysogenic Cycles of Bacteriophages

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https://youtu.be/AAqiblRo-mU?si=PzAcHLFHfkhhfoDP

slight accent, but good explanation

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Physical and Chemical Agents of Microbial Control