Studies on UV mutational breeding of Lactococcus lactis V528 for producing bacteriocin-like substance

Objective To select mutants with high productivity of anti-Salmonella pullorum bacteriocin-like substance.Methods The cells of Lactococcus lactis V528,in the late exponential phase,were mutated by ultraviolet radiation with 82.7% death rate.The colonies of 117 and 310 were seleted for testing the antibacterial titer of the culture supernatant,after radiated by the first time and sencond time respectively.Results Under this condition,the numbers of positive mutants had some content predominance over negative ones.And among them,the bacteriocin-like substance yield of strain Lact.174 was 8.48 times more than the original strain with stable inheritance.Conclusion Mutants with high productivity of bacteriocin-like substance were got efficiently by UV mutational breeding.