Industrially important microorganisms and their applications MCQs With Answer
This collection of MCQs is tailored for M.Pharm students studying Microbial and Cellular Biology (MPB102T). It covers key industrial microorganisms—bacteria, fungi, yeast and actinomycetes—and their roles in producing antibiotics, enzymes, organic acids, amino acids, vitamins and recombinant therapeutics. Questions emphasize practical aspects: choice of organism, fermentation modes, upstream strain improvement, immobilization, downstream processing and quality considerations. These items are designed to deepen conceptual understanding and prepare students for exams and industry-relevant problem solving by linking microbial physiology, bioprocess parameters and product recovery strategies.
Q1. Which microorganism is most widely used for industrial production of citric acid?
- Penicillium chrysogenum
- Aspergillus niger
- Saccharomyces cerevisiae
- Bacillus subtilis
Correct Answer: Aspergillus niger
Q2. Which genus is the main source of many clinically important antibiotics such as streptomycin and tetracycline?
- Clostridium
- Streptomyces
- Escherichia
- Lactobacillus
Correct Answer: Streptomyces
Q3. Which microorganism is commonly used for industrial-scale ethanol fermentation from sugars?
- Saccharomyces cerevisiae
- Aspergillus oryzae
- Corynebacterium glutamicum
- Pseudomonas putida
Correct Answer: Saccharomyces cerevisiae
Q4. Which organism is the primary industrial producer of penicillin?
- Penicillium chrysogenum
- Penicillium notatum
- Aspergillus niger
- Streptomyces griseus
Correct Answer: Penicillium chrysogenum
Q5. Corynebacterium glutamicum is industrially important for production of which compound?
- Citric acid
- Lactic acid
- Glutamic acid (L-glutamate)
- Penicillin
Correct Answer: Glutamic acid (L-glutamate)
Q6. Which microorganism is frequently used as a recombinant host for therapeutic proteins due to well-known genetics and fast growth?
- Lactobacillus acidophilus
- Escherichia coli
- Rhizopus oryzae
- Streptococcus thermophilus
Correct Answer: Escherichia coli
Q7. Which fermentation mode allows feeding substrate during cultivation to avoid substrate inhibition and often increases product yield?
- Batch fermentation
- Fed-batch fermentation
- Solid-state fermentation
- Static culture
Correct Answer: Fed-batch fermentation
Q8. The Monod equation describes the relationship between microbial growth rate and substrate concentration; which parameter represents the substrate concentration at which growth rate is half of μmax?
- μmax
- Kd
- Ks (half-saturation constant)
- Yxs (yield coefficient)
Correct Answer: Ks (half-saturation constant)
Q9. Which enzyme source is credited with enabling PCR by providing a thermostable DNA polymerase?
- Escherichia coli T7 polymerase
- Thermus aquaticus (Taq polymerase)
- Bacillus subtilis protease
- Saccharomyces cerevisiae reverse transcriptase
Correct Answer: Thermus aquaticus (Taq polymerase)
Q10. Immobilization of microbial cells is commonly used in industry for which main advantage?
- To ensure genetic modification of cells
- To increase cell washout in continuous reactors
- To allow cell reuse and improve operational stability
- To make cells more susceptible to phage infection
Correct Answer: To allow cell reuse and improve operational stability
Q11. Which organism is a principal industrial producer of citric acid by submerged fermentation using sugar substrates?
- Saccharomyces boulardii
- Aspergillus niger
- Trichoderma reesei
- Bacillus licheniformis
Correct Answer: Aspergillus niger
Q12. Which bacterium is widely used in industry for production of industrial proteases and amylases due to its secretion capacity and GRAS status?
- Bacillus subtilis
- Staphylococcus aureus
- Pseudomonas aeruginosa
- Clostridium perfringens
Correct Answer: Bacillus subtilis
Q13. Pseudomonas species are industrially exploited for production of what type of biomolecules useful in bioremediation and detergents?
- Biosurfactants and biodegradation enzymes
- Essential amino acids
- Cellulose fibers
- Penicillins
Correct Answer: Biosurfactants and biodegradation enzymes
Q14. Which downstream processing technique is most suitable for initial recovery and concentration of microbial biomass or cells from fermentation broth?
- Gel permeation chromatography
- Centrifugation
- Lyophilization
- Affinity chromatography
Correct Answer: Centrifugation
Q15. Which fungal species is commonly used for industrial production of enzymes like xylanases and cellulases for biomass hydrolysis?
- Aspergillus niger
- Penicillium chrysogenum
- Trichoderma reesei
- Saccharomyces cerevisiae
Correct Answer: Trichoderma reesei
Q16. Which microorganism is the preferred industrial producer of L-lysine and other amino acids due to its metabolic properties?
- Corynebacterium glutamicum
- Streptococcus pneumoniae
- Escherichia coli K-12
- Bacillus anthracis
Correct Answer: Corynebacterium glutamicum
Q17. What is the primary purpose of strain improvement in industrial microbiology?
- To reduce the need for downstream processing
- To decrease fermentation volume only
- To enhance yield, productivity or product quality
- To increase contamination risk
Correct Answer: To enhance yield, productivity or product quality
Q18. Which of the following is a common method used for sterilization of heat-sensitive fermentation media or air in bioreactors?
- Autoclaving at 121°C for 15 minutes
- Dry heat sterilization at 180°C
- Membrane filtration (0.22 μm filters)
- Gamma irradiation of the assembled fermenter
Correct Answer: Membrane filtration (0.22 μm filters)
Q19. In industrial vitamin B12 production, which microorganism has historically been utilized as a primary producer?
- Pseudomonas denitrificans
- Saccharomyces cerevisiae
- Aspergillus niger
- Bacillus subtilis
Correct Answer: Pseudomonas denitrificans
Q20. Which parameter is most critical to control in aerobic fermentations to ensure sufficient oxygen transfer for high cell density cultures?
- pH only
- Agitation speed and aeration rate (oxygen transfer rate, kLa)
- Light intensity
- Presence of antibiotics
Correct Answer: Agitation speed and aeration rate (oxygen transfer rate, kLa)
