嗜线虫致病杆菌北京变种的型变进程及抗生素相关性质的研究

Studies on Phase Variation Process and Antibiotics-related Properties of Xenorhabdus Nematophila Var. Pekingensis Strain

嗜线虫致病杆菌是小卷蛾斯氏线虫体内的共生细菌,在实验室条件下延长培养将会出现型态变异,即从野生型的I型细胞变为II型细胞。对嗜线虫致病杆菌北京变种的型变进程进行了研究,结果发现,嗜线虫致病杆菌北京变种I型菌株在LB培养基中培养4 d即有II型菌出现;培养10 d后,II型菌的比例超过50%;培养到22 d时,II型菌在整个NBTA平板中的比例几乎达到95%。然后分别以I型菌株和II型菌株为材料,对其产素能力和抗生素抗性水平进行了比较,结果显示,北京变种II型菌株对枯草芽孢杆菌的抑制水平降低到I型菌的10.08%;2种型态的菌株均对青霉素和氨苄青霉素具有抗性,其中I型菌株的耐受程度高于II型菌株,因此,嗜线虫致病杆菌北京变种2型细胞的产抗生素能力差异与抗生素抗性水平差异之间可能存在相关性。

The process of phase variation of X. nematophila var. pekingensis was studied. The results showed that, during the course of consistent incubation in BL broth, phase Ⅰ strain to transit into phase Ⅱ one at 4 days. the percentage of phase Ⅱ strains in media was 50% at 10 days, and 95% at 22 day, respectively. Meanwhile the antibiotics producing abilities and antibiotics resistance levels of two phases of bacteria were investigated. It was revealed that, the inhibitory ability of phase Ⅱ strain against Bacillus subtilis was decreased rapidly to 10. 08% of that of phase Ⅰ cells. Either of two phases of strain was resistant to penicillin and ampicillin. However phase Ⅰ cells demonstrated the higher resistance degree than phase Ⅱ cells of this strain. The results implied the possible relationship between of antibiotics producing ability and resistance level in different phases of Xenorhabdus nematophila var. pekingensis strain.