STM 422 – Industrial Microbiology OSUNTECHCOLLEGE 2022/2023 Second Semester Examination

ANSWER:

Question 1a:

As a microbiologist, you are required to compound your industrial media with some raw materials before use. List and explain some of the raw materials you will use in compounding your industrial media.

Answer:
Some raw materials used in industrial media formulation include:

1. Carbon Sources: Provides energy for microbial growth (e.g., glucose, sucrose, starch).
2. Nitrogen Sources: Essential for protein synthesis (e.g., peptone, ammonium salts, yeast extract).
3. Mineral Salts: Maintain osmotic balance and enzymatic function (e.g., magnesium sulfate, potassium phosphate).
4. Vitamins and Growth Factors: Enhance microbial metabolism (e.g., biotin, riboflavin).
5. Water: Serves as a solvent and supports microbial metabolism.

Question 1b:

Explain alcohol fermentation by yeast.

Answer:
Alcohol fermentation is a biological process where yeast, primarily Saccharomyces cerevisiae, converts sugars such as glucose and fructose into ethanol and carbon dioxide under anaerobic conditions. The reaction follows:

C6H12O6→2C2H5OH+2CO2+EnergyC_6H_{12}O_6 \rightarrow 2C_2H_5OH + 2CO_2 + Energy

This process is widely used in brewing, winemaking, and bioethanol production.

Question 1c:

Write five characteristics of an ideal industrial culture media.

Answer:
An ideal industrial culture media should:

1. Provide essential nutrients (carbon, nitrogen, vitamins, and minerals).
2. Support maximum microbial growth for high yield production.
3. Maintain a stable pH for optimal enzyme activity.
4. Be free of contaminants to prevent unwanted microbial growth.
5. Be cost-effective and easily available for large-scale industrial use.

Question 2:

Explain explicitly Saccharomyces cerevisiae as an industrial microorganism.

Answer:
Saccharomyces cerevisiae is a yeast widely used in industrial microbiology due to its ability to:

1. Ferment sugars to produce ethanol in brewing and winemaking.
2. Act as a leavening agent in baking by producing carbon dioxide.
3. Produce bioethanol, a renewable energy source.
4. Synthesize valuable enzymes such as invertase and proteases.
5. Serve as a model organism in scientific research due to its well-understood genetics.

Question 3a:

Compare and contrast batch culture and continuous culture.

Answer:

Question 3b:

List the major classes of antimicrobial agents.

Answer:

1. Antibiotics (e.g., penicillin, streptomycin)
2. Antifungals (e.g., amphotericin B, fluconazole)
3. Antivirals (e.g., acyclovir, remdesivir)
4. Antiparasitics (e.g., metronidazole, chloroquine)
5. Disinfectants and antiseptics (e.g., alcohol, chlorine)

Question 4a:

State four reasons for cultivating industrial microorganisms.

Answer:

1. Production of antibiotics (e.g., Penicillium for penicillin).
2. Fermentation for food and beverages (e.g., yeast for beer and bread).
3. Biotechnology applications (e.g., genetically modified bacteria for insulin production).
4. Environmental applications (e.g., bioremediation for pollution control).

Question 4b:

Complete the table.

Question 5a:

With the aid of a good flowchart, write concisely on the production of “Garri.”

Answer:

1. Harvesting – Cassava tubers are harvested.
2. Peeling and Washing – The tubers are peeled and washed.
3. Grinding – The cassava is ground into a pulp.
4. Fermentation – The pulp is left to ferment for 24-48 hours.
5. Dewatering – Excess water is removed using a press.
6. Sieving – The dewatered mass is sieved to remove large particles.
7. Frying – The sieved cassava is roasted to form garri.

Question 5b:

Differentiate between spontaneous fermentation and induced fermentation.

Answer:

• Spontaneous fermentation occurs naturally without adding specific microorganisms (e.g., traditional sourdough bread).
• Induced fermentation involves the deliberate addition of microorganisms to control the process (e.g., yeast in beer production).

Question 6a:

Highlight the source of material for the production of the following alcoholic beverages.

Question 6b:

Give four reasons for boiling worts in beer production.

Answer:

1. Sterilization – Kills unwanted microorganisms.
2. Enzyme inactivation – Stops enzyme activity at the right stage.
3. Hop extraction – Extracts flavors and bitterness from hops.
4. Concentration – Reduces water content to achieve desired concentration.

Question 6c:

List three types of microbiological methods in amino acid manufacture.

Answer:

1. Fermentation process (e.g., lysine production using Corynebacterium glutamicum).
2. Enzymatic synthesis (e.g., glutamate production).
3. Genetic engineering (e.g., recombinant DNA technology).

Question 7a:

Briefly explain the first five steps involved in the beer production process.

Answer:

1. Malting – Barley grains are germinated and dried.
2. Mashing – Malted barley is mixed with hot water to extract sugars.
3. Lautering – Solid grains are separated from the liquid wort.
4. Boiling – The wort is boiled and hops are added.
5. Fermentation – Yeast is added to convert sugars into alcohol.

Question 7b:

Differentiate between beer and wine based on the given factors.

Question 7c:

What is an alcoholic beverage?

Answer:
An alcoholic beverage is a drink that contains ethanol, produced by the fermentation of sugars by yeast. Examples include beer, wine, and spirits.