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2. How are photoautotrophs and photoheterotrophs similar and how do they differ?

3. Group the photosynthetic bacteria according to its trophy and oxygenic/anoxygenic phototrophs.

Secondary Metabolites questions and answers:

1. Secondary metabolite

2. How is the secondary metabolite produced?  

3. Relate primary and secondary metabolism of the secondary  metabolite.

4. Which microbes is it from and what other microbes produce this secondary metabolite?

Muthiah Nuri Rahmani (A180504)

Siti Fatihah Hidayatul Binti Halim (A18SC0475)

Fatin Natasha Binti Yusof (A18SC0392)

Sterilize all the above contents and fed into the stirred tank fermentor. Then, transfer the bacterial inoculum of about 4-5% to the medium. Maintain a temperature between the range of 25-30 degrees Celsius and pH between 7.6-8 inside the fermentor. The production of streptomycin requires continuous fermentation, and the growth of S.griseus requires continuous aeration and agitation. The fermentation process takes 4-10 days. The fermentation process involves three consecutive phases.

During the first phase, the S.griseus grows by utilizing soya meal and releases ammonia through proteolytic activity. The pH rises during this phase. S.griseus slowly utilizes the carbon source present in the soy meal and the glucose and thereby producing streptomycin at a slower rate.

After the utilization of soy meal and glucose, the ammonia is secreted, and the streptomycin is synthesized rapidly. In this phase, the incubation period lasts for 24 hours to 6-7 days. The pH during this phase remains constant between 7.6 and 8. There is little or no production of mycelium.

It is the final phase of fermentation, where the concentration of glucose depletes from the medium that results in cessation of streptomycin production, and the bacterial cells begin to lyse. As a result, the medium’s pH increases by the deposition of ammonia after the cell lysis. Before cell lysis, harvest the fermentative medium for the process of recovery and purification.

Antibiotics are products of secondary metabolism from streptomycin that inhibit the growth of other microorganisms even at low concentrations. To be able to obtain secondary metabolites, metabolic pathway reaction methods are conducted using multienzyme complexes or an individual enzyme. It is generally believed that secondary metabolism is derived from primary metabolism by gene duplication and possibly by allelic divergence. The primary mechanism of action is inhibition of translation by binding to the ribosome. 

Original microbe producing streptomycin: Streptomyces griseus

Other: Streptomyces glaucescens

1) For what two purposes are inorganic compounds used by chemolithotrophs?

2) Why are the sulphur-oxidizing lithotrophs typically acidophiles?

3) What is the function of rusticyanin and where is it found in the cell?

4) What is the inorganic electron donor for Nitrosomonas? For Nitrobacter?

5) What do nitrifying bacteria use as a carbon source? 

6) What is the anammox reaction and how does it differ from aerobic nitrification?

a) With every breath you take, thank the ocean. Based on this statement, discuss the diversity of microorganisms and its metabolism that are responsible for giving us the means to breathe. (10 marks).

i) Describe and explain the metabolism of this microorganism (8 marks)

Removal of sulfide minerals is defined as oxidation of sulfide by the microbes. The metabolism of this microorganism is chemolithoautotrophic. This microbe obtains energy from chemical compounds and since the organic nutrients are extremely low, it can derive the energy from the inorganic compound which in this case is sulfide by oxidation of sulfide to sulfate. The oxidation of sulfide can occur in two ways which are aerobically and anaerobically. Aerobically, the oxidation can occur in substrate-level phosphorylation depending on AMP (transfer phosphate group to ADP to produce ATP) or in oxidative phosphorylation (ETC) where the sulfide acts as electron donor and oxygen as electron acceptor to produce ATP. Anaerobically, sulfide will oxidize to sulfate by using nitrate as terminal electron acceptor which then reduces to dinitrogen in ETC with the help of sulfite oxidase enzyme. Since organic nutrients are low, this microbe can only obtain carbon source from inorganic carbon, which is through carbon dioxide fixation (calvin cycle) using the energy source from the oxidation of sulfide. It can also use the energy of the reducing power from reverse electron flow using sulfur as a higher redox potential that can reduce NAD+ to NADH. NADH is then used in the calvin cycle for carbon source. Thus, it is considered as autotroph.  Example of bacteria is thiobacillus thiooxidans. 

ii) What is the primary and secondary product of the microorganism? (2 marks)

NADH as primary product while ATP as secondary product.

iii) List the application use for this type of metabolism. (2 marks)

Bioleaching or biomining