Bioprocessing of vitamin B12 MCQs With Answer

Introduction

Bioprocessing of vitamin B12 is a crucial subject for M.Pharm students focusing on industrial biotechnology and pharmaceutical production. This collection of MCQs explores microbial production routes, biosynthetic requirements, fermentation strategies, downstream processing, and analytical and regulatory aspects relevant to pharmaceutical-grade cobalamin. Questions emphasize practical process parameters—such as choice of microorganism, cobalt supplementation, aeration, pH control, and fed‑batch design—along with purification steps like cyanidation and ion‑exchange chromatography. The quiz combines fundamental bioscience (corrin ring assembly, lower ligand chemistry) with applied engineering concepts (scale‑up considerations, assay methods and quality specifications), preparing students for research or industry roles in vitamin B12 manufacture.

Q1. Which microorganism is classically used in aerobic industrial production of vitamin B12?

• Pseudomonas denitrificans
• Propionibacterium freudenreichii
• Saccharomyces cerevisiae
• Bacillus subtilis

Correct Answer: Pseudomonas denitrificans

Q2. What is the central structural feature of vitamin B12 that coordinates cobalt?

• Corrin ring
• Porphyrin ring
• Flavin ring
• Chlorin ring

Correct Answer: Corrin ring

Q3. Which trace element is essential in the biosynthesis of cobalamin?

• Cobalt
• Zinc
• Chromium
• Nickel

Correct Answer: Cobalt

Q4. Which chemical form of vitamin B12 is most commonly produced and used as a stable pharmaceutical ingredient?

• Cyanocobalamin
• Methylcobalamin
• Adenosylcobalamin
• Hydroxocobalamin

Correct Answer: Cyanocobalamin

Q5. In downstream processing of microbial B12, why is a cyanidation step often applied?

• To convert various corrinoid species into the stable form cyanocobalamin
• To precipitate protein impurities selectively
• To denature cells for easier filtration
• To sterilize the product stream

Correct Answer: To convert various corrinoid species into the stable form cyanocobalamin

Q6. Which analytical technique is the preferred modern method for quantifying and profiling cobalamin vitamers in fermentation broths?

• HPLC (High‑Performance Liquid Chromatography)
• Thin layer chromatography (TLC)
• Colorimetric diazotization
• UV absorbance of crude broth

Correct Answer: HPLC (High‑Performance Liquid Chromatography)

Q7. The biosynthetic pathways for cobalamin can be aerobic or anaerobic. Which organism is known to use the aerobic pathway?

• Pseudomonas denitrificans
• Propionibacterium freudenreichii
• Clostridium species
• Escherichia coli (native)

Correct Answer: Pseudomonas denitrificans

Q8. Biosynthesis of cobalamin branches from which common tetrapyrrole intermediate?

• Uroporphyrinogen III
• Heme
• Chlorophyllide
• Biliverdin

Correct Answer: Uroporphyrinogen III

Q9. For many industrial cobalamin fermentations using Pseudomonas, what is the typical optimal pH range maintained during production?

• 6.5–7.5
• 4.0–5.0
• 8.5–9.5
• 3.0–4.0

Correct Answer: 6.5–7.5

Q10. Addition of which supplement is most directly linked to increased intracellular cobalamin synthesis in fermentation media?

• Cobalt salts (e.g., CoCl2)
• High concentrations of glucose only
• Exogenous heme
• Calcium carbonate

Correct Answer: Cobalt salts (e.g., CoCl2)

Q11. What is a principal advantage of fed‑batch fermentation for vitamin B12 production compared with simple batch mode?

• Allows controlled substrate feeding to prevent catabolite repression and substrate inhibition, increasing yield
• Requires less process control and monitoring
• Eliminates the need for aeration
• Shortens total fermentation time dramatically

Correct Answer: Allows controlled substrate feeding to prevent catabolite repression and substrate inhibition, increasing yield

Q12. Dimethylbenzimidazole (DMBI) plays what role in cobalamin structure?

• It is the lower axial ligand/base attached to the cobalt
• It forms the corrin macrocycle
• It is the upper adenosyl ligand
• It is a cofactor for cobalt insertion enzymes

Correct Answer: It is the lower axial ligand/base attached to the cobalt

Q13. Which chromatographic technique is frequently used in purification schemes for pharmaceutical cyanocobalamin because of its charge properties?

• Ion‑exchange chromatography
• Gel filtration chromatography
• Normal phase chromatography
• Affinity chromatography using antibody columns

Correct Answer: Ion‑exchange chromatography

Q14. Which environmental factor is known to cause significant degradation of cobalamin if not controlled during processing?

• Light exposure and strong alkaline conditions
• Low oxygen tension alone
• High atmospheric CO2
• Elevated levels of nitrogen gas

Correct Answer: Light exposure and strong alkaline conditions

Q15. Which fermentation mode is most commonly implemented at industrial scale for maximizing cobalamin productivity and control?

• Fed‑batch fermentation
• Simple batch fermentation without feed
• Continuous chemostat with no recycling
• Solid state fermentation

Correct Answer: Fed‑batch fermentation

Q16. Which natural coenzyme form of B12 is specifically required by methionine synthase in humans?

• Methylcobalamin
• Adenosylcobalamin
• Cyanocobalamin
• Hydroxocobalamin

Correct Answer: Methylcobalamin

Q17. What is the main purpose of converting fermentation corrinoids into cyanocobalamin during downstream processing?

• Standardize product to a chemically stable and pharmacopeial form for formulation
• Remove residual cobalt from the molecule
• Increase the molecular weight for easier filtration
• Deactivate microbial contaminants

Correct Answer: Standardize product to a chemically stable and pharmacopeial form for formulation

Q18. Which method provides the highest specificity for detecting and quantifying individual cobalamin vitamers in a finished sample?

• LC‑MS/MS (Liquid Chromatography–Tandem Mass Spectrometry)
• Biological microbiological assay only
• Simple UV spectrophotometry of crude extract
• Paper chromatography

Correct Answer: LC‑MS/MS (Liquid Chromatography–Tandem Mass Spectrometry)

Q19. Why are antibiotics generally avoided during large‑scale industrial fermentation for pharmaceutical vitamin B12 production?

• Antibiotic residues complicate downstream purification and regulatory acceptance
• Antibiotics always enhance cobalamin production which is undesirable
• They accelerate cobalt incorporation into corrinoids
• Antibiotics permanently sterilize the product, making recovery impossible

Correct Answer: Antibiotic residues complicate downstream purification and regulatory acceptance

Q20. Pharmaceutical specifications for cyanocobalamin often reference which pharmacopeial standards for potency and purity?

• USP/EP (United States Pharmacopeia / European Pharmacopoeia)
• AOAC only
• WHO traditional medicine monographs exclusively
• NFPA industrial chemical code

Correct Answer: USP/EP (United States Pharmacopeia / European Pharmacopoeia)

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