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Lysine is being produced in a lab-scale reactor by a threonine auxotroph. After 2 weeks of operation it was observed that the concentration of lysine in the reactor was gradually decreasing. Microbiological assays of reactor samples showed absence of contamination and recorded data showed no change in the operating conditions. The most probable reason for decrease in lysine concentration may be attributed to
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- accumulation of ethanol
- growth of revertants
- production of citric acid
- unutilized phosphoenol pyruvate
Correct Option: B
In a lab-scale bioreactor, lysine is produced from threonine auxotroph but it was found that concentration of lysine was gradually decreasing. The most probable reason was found to be revertants. Reversion is the process by which mutant DNA is changed so that the protein inactivated by the first mutation is reactivated by the second. There are three classes of reversion: Class I, class II and class III. Revertant is a mutant gene, individual, or strain that regains a former capability (as the production of a particular protein) by undergoing further mutation.
