Bioprocessing of lysine MCQs With Answer

Bioprocessing of lysine MCQs With Answer

This blog presents a focused set of multiple-choice questions on the bioprocessing of L-lysine tailored for M.Pharm students. It covers microbial strains, metabolic pathways, strain improvement strategies, fermentation modes and control, substrate and nutrient choices, process kinetics, analytical techniques, and downstream purification methods. Questions probe both fundamental biochemical regulation (e.g., feedback inhibition in the diaminopimelate pathway) and applied engineering concepts (e.g., fed‑batch strategy, oxygen transfer, and ion‑exchange recovery). Each question is followed by four options and a clear answer to help students prepare for exams and practical design problems in bioprocess engineering and technology.

Q1. Which microorganism is the primary industrial workhorse for commercial production of L-lysine?

• Bacillus subtilis
• Escherichia coli
• Corynebacterium glutamicum
• Streptomyces coelicolor

Correct Answer: Corynebacterium glutamicum

Q2. Which enzyme is the key regulatory point subject to feedback inhibition by lysine in the aspartate-derived biosynthetic pathway?

• Dihydrodipicolinate synthase (DapA)
• Aspartokinase (AK)
• Homoserine dehydrogenase
• Diaminopimelate decarboxylase

Correct Answer: Aspartokinase (AK)

Q3. Through which biosynthetic route is L-lysine produced in Corynebacterium and most bacteria?

• Shikimate pathway
• Urea cycle
• Diaminopimelate (DAP) pathway
• Transaminase I pathway

Correct Answer: Diaminopimelate (DAP) pathway

Q4. Which genetic modification is commonly used to relieve feedback inhibition and increase lysine flux?

• Knockout of lysA (lysine decarboxylase)
• Introduction of a feedback-resistant aspartokinase (lysC*)
• Overexpression of glutamate dehydrogenase
• Deletion of the lysine export system

Correct Answer: Introduction of a feedback-resistant aspartokinase (lysC*)

Q5. What fermentation mode is most commonly used industrially to achieve high lysine titers and productivity?

• Batch fermentation
• Continuous chemostat
• Fed-batch fermentation
• Solid‑state fermentation

Correct Answer: Fed-batch fermentation

Q6. Which carbon source is typically preferred for large-scale lysine fermentations due to high yield and easy control?

• Lactose
• Glucose
• Glycerol
• Cellulose hydrolysate

Correct Answer: Glucose

Q7. Which nitrogen source is commonly used in industrial lysine media to support high cell density and product formation?

• Peptone
• Ammonium sulfate
• Nitrate salts
• Urea

Correct Answer: Ammonium sulfate

Q8. At what pH range is lysine fermentation with Corynebacterium glutamicum typically maintained for optimal production?

• pH 4.5–5.5
• pH 6.0–6.5
• pH 7.0–7.5
• pH 8.5–9.0

Correct Answer: pH 7.0–7.5

Q9. What is the typical cultivation temperature for optimal growth and lysine synthesis by industrial Corynebacterium strains?

• 20°C
• 30°C
• 37°C
• 45°C

Correct Answer: 30°C

Q10. What oxygen condition is essential for high-yield lysine fermentation?

• Anaerobic conditions
• Microaerophilic conditions with low agitation
• Strictly aerobic with high oxygen transfer rate
• Intermittent anaerobic/aerobic cycling

Correct Answer: Strictly aerobic with high oxygen transfer rate

Q11. Which common amino acid by-product often accumulates during lysine fermentations if metabolic balance shifts?

• L-serine
• L-glutamate
• L-tryptophan
• L-alanine

Correct Answer: L-glutamate

Q12. Which analytical technique is most appropriate for accurate quantification of L-lysine in fermentation broth?

• UV absorbance at 280 nm
• Gas chromatography without derivatization
• HPLC with pre‑column derivatization (e.g., OPA)
• Infrared spectroscopy

Correct Answer: HPLC with pre‑column derivatization (e.g., OPA)

Q13. Which downstream technique is widely used to capture and purify lysine from clarified fermentation broth?

• Size exclusion chromatography
• Anion-exchange chromatography
• Cation-exchange chromatography
• Hydrophobic interaction chromatography

Correct Answer: Cation-exchange chromatography

Q14. In industrial processing, lysine is often isolated and marketed as which stable salt form?

• L-lysine sulfate
• L-lysine monohydrochloride (L-lysine·HCl)
• L-lysine ethyl ester
• L-lysine free base oil

Correct Answer: L-lysine monohydrochloride (L-lysine·HCl)

Q15. How is volumetric productivity of a lysine fermentation expressed?

• g of lysine per g of biomass
• g of lysine per L per hour (g/L/h)
• moles of lysine per mole of glucose
• percentage purity of final crystals

Correct Answer: g of lysine per L per hour (g/L/h)

Q16. What unit is commonly used to express yield of lysine from glucose in a fermentation process?

• g lysine per L broth
• g lysine per g glucose (g/g)
• mol lysine per L medium
• cells per mL

Correct Answer: g lysine per g glucose (g/g)

Q17. Which antimetabolite has historically been used to select for lysine-overproducing mutants?

• Azaserine
• S-(2-aminoethyl)-L-cysteine (AEC)
• 5‑Fluorouracil
• Streptomycin

Correct Answer: S-(2-aminoethyl)-L-cysteine (AEC)

Q18. Which enzyme catalyzes the condensation step converting aspartate semialdehyde toward the diaminopimelate branch leading to lysine?

• Aspartate kinase
• Dihydrodipicolinate synthase (DHDPS, DapA)
• Diaminopimelate decarboxylase
• Threonine synthase

Correct Answer: Dihydrodipicolinate synthase (DHDPS, DapA)

Q19. To increase precursor supply (oxaloacetate) for lysine biosynthesis, which metabolic engineering intervention is commonly applied?

• Overexpress pyruvate dehydrogenase (PDH)
• Knockout of phosphofructokinase
• Overexpress phosphoenolpyruvate carboxylase (ppc)
• Overexpress citrate synthase

Correct Answer: Overexpress phosphoenolpyruvate carboxylase (ppc)

Q20. Which mathematical model relates product formation rate to microbial growth rate and is often used to describe lysine production kinetics?

• Monod model only
• Michaelis–Menten kinetics
• Luedeking–Piret model
• Henderson–Hasselbalch equation

Correct Answer: Luedeking–Piret model

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