八株芽孢杆菌的分离鉴定及其抗逆性比较

Isolation and identification of 8 strains of Bacillus and comparison of their resistance

从土壤中分离到3个菌株,分别命名为KF、DY和LB1,从猪粪便中分离到5个菌株,分别命名为KH、K2X、KY1、LB2和LY3,通过16SrRNA基因序列分析,结合细菌形态学、生理生化特性进行了鉴定,并对分离菌的抗逆性进行了比较。经鉴定,KF、KH、K2X和KY1菌株为枯草芽孢杆菌,LB1、LB2和LY3菌株为蜡样芽孢杆菌,DY菌株为地衣芽孢杆菌;抗逆性比较结果显示,K2X菌株对温度比较敏感,其他菌株经60℃处理30min后不影响其生长;DY菌株耐酸性最强,能在pH3的胃液中正常生长;KY1菌株的耐酸性次之,耐胆盐能力最强,能在胆盐含量为6g/L的培养基和模拟肠液中正常生长。研究还发现,这8个菌株对共培养的大肠杆菌都没有抑制作用,只有KF、KH和LB2菌株对共培养的沙门氏菌分别有28.6%、27.0%和24.6%的抑菌效果。

Strains named KF,DY and LB1were isolated from soil,and strains named KH,K2X,KY1, LB2and LY3were isolated from the faeces of healthy pigs.According to the results of morphological observation,physiological and biochemical tests,and sequence analysis of the 16S rRNA gene,strains KF, KH,K2X and KY1 were identified to be Bacillussubtilis,LB1,LB2 and LY3to be Bacillus cereus,and DY to be Bacillus licheniformis.Stress resistances of all strains were examined.The results showed that K2X was sensitive to temperature,and the other seven strains grew normally after treatment at 60℃for 30min. DY had the strongest acid-resistant ability,and it regularly grew in the simulated gastric juice with pH 3.0.KY1 strain resisted both the acid with pH 4.0and the bile salt of 6g/L,and it regularly grew in the simulated intestinal fluid.Inhibiting rates of KF,KH and LB2strains to Salmonella were 28.6%,27.0%and 24.6%,respectively,but the eight Bacillus strains of did not inhibit the growth of Escherichia coli O157.