Biosynthesis of Nisin A by a Bacitra-cin-Resistant Strain of <i>Lactococcus lactis</i>
A spontaneous bacitracin-resistant (Bcr<sup>R</sup>) strain derived from a bacitracin-sensitive culture of <i>Lactococcus lactis </i>VKPM В-7699 has been shown to have a higher productivity for nisin, greater growth and lactose consumption rates and resistance to oxidative stress in comparison with the original strain. Both strains do not differ in casein-protease activity. The Bcr<sup>R</sup> strain retains the sensitivity to a range of cell-wall inhibiting antibiotics. Possible mechanisms for the bcr<sup>11</sup> mutation influence on the nisin biosynthesis are discussed.