Q.18 In a batch culture of Penicillium chrysogenum, the maximum penicillin synthesis occurs during the
(A) lag phase
(B) exponential phase
(C) stationary phase
(D) death phase
Penicillin synthesis by Penicillium chrysogenum peaks during the stationary phase in batch cultures. This secondary metabolite production aligns with microbial growth kinetics in biotechnology.
Correct Answer
The correct answer is (C) stationary phase. Maximum penicillin production happens here as cells shift from rapid growth to metabolite synthesis under nutrient limitation.
Growth Phases Explained
Batch cultures of Penicillium chrysogenum follow standard microbial phases: lag, exponential, stationary, and death.
-
Lag phase (A): Cells adapt to the medium with minimal growth or product formation; no significant penicillin synthesis occurs due to low metabolic activity.
-
Exponential phase (B): Rapid biomass increase dominates; penicillin production starts but remains low as resources fuel cell division.
-
Stationary phase (C): Growth halts due to nutrient depletion; secondary metabolites like penicillin peak as enzymes activate under stress.
-
Death phase (D): Cell lysis prevails; production declines sharply with no viable synthesis.
Biotechnology Relevance
Penicillin, a β-lactam antibiotic, forms via pathways involving ACVS, IPNS, and IAT enzymes in fungal microbodies and cytosol. Industrial strains optimize stationary phase yields through controlled fermentation at 25-26°C. This knowledge aids bioprocess engineering for antibiotic production.
