Meijer, W; Van-De-Bunt, B; Twigt, M; De-Jonge, B; Smit, G; Hugenholtz, J

Applied and Environmental Microbiology [Appl. Environ. Microbiol.], vol. 64, no. 5, pp. 1950-1953, May 1998

To develop a nisin-producing cheese starter, Lactococcus lactis subsp. cremoris SK110 was conjugated with transposon Tn5276-NI, which codes for nisin immunity but not for nisin production. Cheese made with transconjugant SK110::Tn5276-NI as the starter was bitter. The muropeptide of the transconjugant contained a significantly greater amount of tetrapeptides than the muropeptide of strain SK110, which could have decreased the susceptibility of the cells to lysis and thereby the release of intracellular debittering enzymes.