Production of Gramicidin S Synthetases by Bacillus brevis in Continuous Culture

Abstract

The effects of different nutrient limitations on the production of 2 enzymes of gramicidin S biosynthesis were studied during continuous culture of B. brevis [to explore the potential of preparative-scale cell-free synthesis of gramicidin S]. Gramicidin S synthetases I and II were produced in the chemostat under C, N, P or S limitation. The growth rate, rather than the nature of the limitation, was the major controlling factor in regulating the level of the gramicidin S synthetases. Synthetase production was low at high dilution rates (0.45-0.50/h) but increased as the dilution rate was lowered. The highest specific activities occurred at dilution rates that were different for each type of limitation: 0.40/h for N, 0.32/h for C, 0.24/h for S and 0.20/h for P. P limitation gave the highest specific activities. At low dilution rates (0.10-0.15/h), enzyme activities were again low. Sporulation occurred under C limitation, but at a lower dilution rate than that which supported optimal gramicidin S synthetase formation. The specific productivity of the synthetases in the chemostat was higher than the highest productivity obtained in batch growth.