Enhancement of Diacetyl Production by a Diacetyl-Resistant Mutant of Citrate-Positive Lactococcus lactis ssp. lactis 3022 and by Aerobic Conditions of Growth

Abstract

Addition of Cu 2 + and Fe 3 + inhibited citrate uptake by citrate-positive Lactococcus lactis ssp. lactis 3022 and stimulated the production of diacetyl, probably because citrate uptake activity of the cells is lowered by diacetyl. A diacetyl-resistant mutant. HK-7, derived from citratepositive L. lactis ssp. lactis 3022, in which diacetyl production was deregulated, produced a larger amount of diacetyl than the parent strain. The mutant also utilized a larger amount of citrate than the parent strain.