Different mutation methods of Lactobacillus acidophilus NX2-6 for improving antifungal activity

Lactobacillus acidophilus NX2- 6 was mutated by60 Co γ irradiation,DES and UV of protoplasts respectively,aiming to obtain high productivity of bacteriocins stains.The results showed that the optimal condition of60 Co γ irradiation was 2.0k Gy,the best mutant condition of DES was the concentration of 0.7% to treat bacteria for 10 min,and the UV of protoplasts best irradiation time was 20 s.Then high productivity strains γ56,D47 and UV125were screened respectively. Moreover,their antibacterial titers were 6096.78,5384.98 U / m L and 6230.79 U / m L. The antibacterial titers of γ56,D47,UV156 was 2.16,1.91,2.21 times than the initial strain( 2819.36 U / m L) respectively. The bacteria passage test indicates that mutant strains γ56,D47,UV156 have the stable heredity.