N^+注入诱变高自溶度的乳酸菌突变株

SCREENING OF LACTIC ACID BACTERIA WITH HIGH AUTOLYSIS RATE BY N^+-IMPLANTATION

通过N+注入方式对乳酸菌唾液链球菌嗜热亚种GS1和德氏乳杆菌保加利亚亚种LD3进行诱变,获得自溶度较高的乳酸菌菌株。离子注入剂量为1×2.6×103～6×2.6×1013时,菌株的存活率曲线呈典型的"马鞍型"剂量-效应曲线,总突变率达到57%～74%。离子注入能量为50keV,最佳注入剂量为4×2.6×1013 ion/cm2,此时,菌体存活率为25%～33%。筛选得到的乳酸菌菌株,自溶度变化幅度在127.98%～-51.96%之间。得到2株自溶度显著提高的突变菌株,分别命名为LD3-A3和GS1-B13,与出发菌株相比其自溶度分别提高了127.98%和115.11%。经5次传代培养,突变株的自溶度和遗传性状比较稳定。结果表明离子注入诱变技术是一种理想的乳酸菌发酵剂菌种选育方法。

In order to obtain lactic acid bacteria with high autolysis rate,Streptococcus salivarius ssp.thermophilus GS1 and Lactobacillus delbrueckii ssp.bulgaricus LD3 were mutated by 50keV N ＋ ions implantation.The results indicated that the survival rate curve took a saddle shape in the range of 1 × 2.6 × 1013 ～ 6 × 2.6 × 1013 and the total mutation rate was 57% ～ 74%.The survival rate were 25% ～ 33% on the suitable dose 4 × 2.6 × 1013 ion/cm2.Among the mutated strains with mutation rate in the range of 127.98% ～-51.96%,the highest autolysis rate mutation strains were named LD3-A3 and GS1-B13.Compare with original strains,autolysis rates of LD3-A3 and GS1-B13 increased by 127.98% and 115.11% respectively.Fermentation properties of LD3-A3 and GS1-B13 were stable after 5 generation transfer inoculation.It indicates that the ion implantation technique is a feasible method in lactic acid bacteria breeding.