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BioTechnology QUESTION #10594
Question 1
The industrial production of L-glutamate by Corynebacterium glutamicum requires a culture condition that triggers product secretion. This is achieved by:
  • Addition of penicillin or biotin limitation to permeabilise the cell membrane✔️
  • Increasing dissolved oxygen tension above 80% saturation
  • Growing cells under strictly anaerobic conditions
  • Adding chloramphenicol to inhibit protein synthesis
Correct Answer Explanation
C. glutamicum normally retains glutamate intracellularly. Secretion is triggered by membrane permeabilisation via: (1) biotin limitation (alters membrane fatty acid composition, reducing membrane integrity), or (2) addition of penicillin (inhibits peptidoglycan synthesis) or detergents. This allows glutamate — produced in excess via the TCA cycle and GOGAT pathway — to leak out, making fermentation profitable. Global MSG production exceeds 2 million tonnes/year.