The stability of the lactose and citrate plasmids in Lactococcus lactis subsp. lactis biovar. diacetylactis
1992
Smith, M.R. | Hugenholtz, J. | Mikoczi, P. | Ree, E. de | Bunch, A.W. | Bont, J.A.M. de
The ability of Lactococcus lactis subsp. lactis biovar. diacetylactis strain C17 to ferment lactose and citrate are stable functions when cells are continuously cultivated under carbon limitation with lactose and citrate present in the medium. Switching the carbohydrate source to glucose rapidly resulted in a population which could no longer ferment lactose. The presence of citrate had no effect on the rapidity of the loss of ability to utilize lactose. The ability of strain C17 to utilize citrate was unaffected by cultivation for more than two weeks on citrate-free medium, containing either lactose or glucose as fermentable carbohydrate. These results confirm the lack of stability of the lactose plasmid and demonstrate for the first time that the citrate plasmid in L. lactis subsp. lactis biovar. diacetylactis is remarkably stable.
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