GENERAL MICROBIOLOGY VM1G2T3 by Khairina Ishak

Biochemical Test

rinaiishak — 2017-03-31 13:07:58 UTC

1. Carbohydrate fermentation test
- Phenol red broth base medium is used as medium. different sugar substrates is added to 100ml of the medium and 5 ml of each mixture is transferred into each tube. for gas detection, durham tube is inserted into the test tube containing glucose. all the tubes are sterilized for 15 mins at 121 Celcius. The reaction of the bacteria is indicated by the changes in the colour of the medium.

Kindly check the video inside.

syuenylim — 2017-03-31 13:09:16 UTC

Biochemical Test

rinaiishak — 2017-03-31 13:21:24 UTC

2. Catalese Test
- To perform this test, a single isolated colony was streaked on the glass slide and one drop of 3% hyrdogen peroxide was added on it. the efferverscence of oxygen indicated the positive response of the bacteria to catalese test.

JOURNAL 1 Lactobacillus acidophilus Alleviates Platelet-Activating Factor-Induced Inflammatory Responses in Human Intestinal Epithelial Cells

jiayi715 — 2017-03-31 13:22:43 UTC

Lactobacillus acidophilus, an important gut commensal, counteracted PAF induction of Bcl10-dependent NF-κB activation and IL-8 production in intestinal epithelial NCM460 and Caco-2 cells.Model below showing mechanisms implicated in alleviating PAF-induced NF-κB activation and IL-8 production in IECs by LA-derived soluble factors.
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0075664

Biochemical Test

rinaiishak — 2017-03-31 13:23:41 UTC

3. Gram Staining Test
The isolated bacteria is examined using gram staining kit according to Collins and colleagues technique and is observed under light microscope with a magnification of 1000x.

Biochemical Test

rinaiishak — 2017-03-31 13:26:15 UTC

4. Two methods Motility Test
4.1 First Method- Hanging-drop wet method:
the slide is observed under a light microscope with 40x magnification to check the motility of the bacteria
4.2 Carigie's Technique
The bacteria is inoculated into the centre of a tube having motility medium using stabbing method. the medium is incubated at two different temperatures of 25 degrees celcius and 37 degree celcius for 48 hours. the Motility of the bacteria is inferren by observing the spreading growth in the incubated semisolid agar.

JOURNAL 2 Effect of probiotic yogurt containing Lactobacillus acidophilus and Bifidobacterium lactis on lipid profile in individuals with type 2 diabetes mellitus

jiayi715 — 2017-03-31 13:28:30 UTC

Probiotic yogurt improved total cholesterol and LDL-C concentrations in type 2 diabetic people and may contribute to the improvement of cardiovascular disease risk factors.. In a randomized double-blind controlled trial, 60 people (23 males and 37 females) with type 2 diabetes and low-density lipoprotein cholesterol (LDL-C) greater than 2.6 mmol/L were assigned to 2 groups. Participants consumed daily 300 g of probiotic yogurt containing Lactobacillus acidophilus La5 and Bifidobacterium lactis Bb12 or 300 g of conventional yogurt for 6 wk. Fasting blood samples, anthropometric measurements and 3-d, 24-h dietary recalls were collected at the baseline and at the end of the trial. Probiotic yogurt consumption caused a 4.54% decrease in total cholesterol and a 7.45% decrease in LDL-C compared with the control group. No significant changes from baseline were shown in triglyceride and high-density lipoprotein cholesterol (HDL-C) in the probiotic group.
http://dx.doi.org/10.3168/jds.2010-4128

Youtube link of Zoom conference

NurHanisahBasuan — 2017-03-31 13:33:59 UTC

JOURNAL 3 Influence of Micro-Encapsulated Probiotic Lactobacillusacidophilus R0052 on the Characteristics of Plain Yogurt

jiayi715 — 2017-03-31 13:35:22 UTC

Micro-encapsulation is a method of providing probiotic living cells with a physical barrier against adverse environmental conditions. Lactobacillus acidophilus is one of the most effective forms of probiotic bacteria and is commercially available as pure culture and encapsulated form. The objective was to determine the influence of micro-encapsulated L. acidophilus on the characteristics of fat free plain yogurt. Yogurts with micro-encapsulated L. acidophilus R0052 had significantly (P < 0.05) higher flavor scores, compared to yogurts with non micro-encapsulated L. acidophilus R0052. The L. acidophilus counts, apparent viscosity, pH and syneresis, of the yogurts with micro-encapsulated L. acidophilus R0052 were not significantly (P < 0.05) different from those of the yogurts with non micro-encapsulated L. acidophilus R0052. Use of micro-encapsulated L. acidophilus R0052 resulted in better tasting yogurts probably because of the taste imparted by the trace amounts of the micro-encapsulating material.
http://file.scirp.org/pdf/AiM20120300021_23015157.pdf

Popplet link of mindmap

NurHanisahBasuan — 2017-03-31 13:35:36 UTC

Name of Microbe adopted

NurHanisahBasuan — 2017-03-31 13:36:59 UTC

Lactobacillus acidophilus

JOURNAL 4 Effect of a fermented milk combining Lactobacillus acidophilus CL1285 and Lactobacillus casei in the prevention of antibiotic-associated diarrhea

jiayi715 — 2017-03-31 13:37:54 UTC

Antibiotic-associated diarrhea is an important problem in hospitalized patients. The main objective of the present study was to assess the efficacy and safety of a fermented milk combining Lactobacillus acidophilus and Lactobacillus casei that is widely available in Canada, in the prevention of antibiotic-associated diarrhea.Among 89 randomized patients, antibiotic-associated diarrhea occurred in seven of 44 patients (15.9%) in the lactobacilli group and in 16 of 45 patients (35.6%) in the placebo group (OR 0.34, 95% CI 0.125 to 0.944; P=0.05). The median hospitalization duration was eight days in the lactobacilli group, compared with 10 days in the placebo group (P=0.09). Overall, the lactobacilli-fermented milk was well tolerated.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2658588/

Morphology

hemalah67 — 2017-03-31 14:19:03 UTC

Size :
0.5-1.2 micrometers by 1.0-10.0 micrometers.

Shape:
consists of rods with rounded ends

Gram stain:
according to Bergey's manual. L. acidophillus, as well as all members of its genus, are Gram-positive.

Grouping:
This microorganism , "Lacto" means milk and "bacillus" means rod like. Acidophillus means it is acid loving.

Morphology

hemalah67 — 2017-03-31 14:28:52 UTC

Cell wall type:
Cell wall consists four important components include peptidoglycan, teichoic acids, S-layer, and polysaccharides. Peptidoglycan (murein) is an essential and specific component of the L. acidophilus cell wall (like othe Gram positive bacteria). It is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane.

Endospore presence:
It is a nonspore forming organism because of the family Lactobacillaceae.

(Lactobacillus sp.)

Metabolism

NurHanisahBasuan — 2017-03-31 14:29:04 UTC

Lactobacillus acidophilus is a homofermentative lactic acid bacteria (LAB) which produce lactic acid as the primary by-product from glucose fermentation.
It grows in anaerobic condition and under pH <3.5.
Since this microbe lacks of cytochromes, porphyrins and respiratory enzymes, it is unable to undergo respiration or oxidative phosphorylation.
Lactobacillus acidophilus is mostly found in high sugar abundance (ex: GI tract in humans & animals) due to its utilization of sugar substrates such as aesculin, cellobiose, galactose, lactose, maltose, salicin, sucrose, glucose and trehalose.
In addition to that, for 1 glucose molecule fermented will results in 2 ATPs of energy yield. Therefore, to generate sufficient energy for their growth, large amounts of substrate needed to be catabolize.
Apart from that, the sugar transport system is sugar-specific and carried out by PEP-PTS and permease system.

Characteristics

nursalsabilakamarudin — 2017-03-31 15:26:10 UTC

1.0 Largest genus of lactic acid bacteria group
--> largest genus over 50 species of lactic acid bacteria group

2.0 Commercially distributed as probiotic
--> WHO defines probiotic as live microorganism which,when administered in adequate amounts,confer a health benefit on the host

3.0 Play important roles in industry
--> contribute in production of various type of cheese,yogurt and many more.
--> Lactobacilli that was produced inhibit the growth of other organisms ,then lowered the pH of the products
--> their metabolic end products contribute the flavor of final food product
--> some of their metabolic reaction intentionally manipulated to breakdown milk protein during cheese production

4.0 Promote beneficial effect on host
--> it limits the growth of undesirable microorganisms
--> it also modulate the immune system of the host

5.0 Homofermantative
--> it promotes sugar into lactic acids
--> then, lactic acid will lowers the pH of products

Ecology

hajarsamsudin95 — 2017-03-31 15:28:19 UTC

Lactobacillus acidophilus is best known as a probiotic. They can grow optimally between 30°C to 40°C. L. acidophilus commonly inhabit the gastrointestinal (GI) tract, oral and vaginal regions of humans and animals.The suggested mechanisms responsible for the probiotic eff ect of L. acidophilus is adherence and colonization. Adherence and colonization of the intestinal epithelium can act in 2 ways:
1. Interaction with enterocytes.
2. Competition for space.

L. acidophilus has been suggested as a supplement for lactose intolerant, when taken orally in sufficient dosages, there is evidence for a decrease in symptoms of lactose maldigestion. This microbacteria that present in yoghurt can colonize the oral cavity because they are able to adhere to enamel. Next, it is known that L. acidophilus is already present in the vagina of healthy women and important in maintaining pH, they also protect against the 'bad' bacteria that cause disease. In GI tract, as a probiotic bacteria it has the potential to influence the existing microbial population in favor of the host's health. Presumably, the L. acidophilus colonizes the GI tract and contributes to the metabolism of lactose digestion and transit through the GI tract.

Lactobacillus acidophilus reproduces using binary fission, a type of asexual reproduction. Binary fission causes the bacterium to double its contents (DNA replicates), the daughter chromosomes moves to opposite poles, cell wall begins to divide, cytoplasm is divided and new cell walls are created, then binary fusion is complete with two separate daughter cells. It is the primary form of reproduction for all bacteria, and can increase the population of the colonies very quickly because each generation doubles.

naili29194 — 2017-04-01 15:22:55 UTC

This is a chart of how many bacteria would be in a colony over the course of one day, if each bacterium split every twenty minutes for an entire day. On the y axis, it shows the numbers in scientific notation, a common way of showing large numbers. At the end of 24 hours, there would be4,722,366,482,869,650,000,000, or 4.7 x 1021 bacteria in the colony.”

naili29194 — 2017-04-01 15:25:50 UTC

The Binary Fission

naili29194 — 2017-04-01 15:31:40 UTC

the binary fission process diaagram

Auni Amirah- Research on Microbe

2017-05-31 08:00:48 UTC

1. https://www.researchgate.net/publication/5402930_Studies_on_Bacillus_subtilis_and_Lactobacillus_acidophilus_as_potential_probiotics_on_the_immune_response_and_resistance_of_Tilapia_nilotica_Oreochromis_niloticus_to_challenge_infections

2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC99697/

3.
http://www.sciencedirect.com/science/article/pii/S1050464808000831

4. http://www.mayoclinic.org/drugs-supplements/acidophilus/evidence/hrb-20058615

5.
http://pennstatehershey.adam.com/content.aspx?productId=107&pid=33&gid=000310