一种XRE家族转录调节因子对干酪乳杆菌适应抗生素环境的影响

Effect of An XRE Family Transcriptional Regulator on the Adaptation of Lactobacillus casei to Antibiotic Environment

摘要:

为了深入研究干酪乳杆菌Zhang（Lactobacillus casei Zhang，L. casei Zhang）在抗生素环境中适应性进化机制，构建基因敲除体系，并对突变体的耐药表型进行研究。运用PCR技术分别扩增XRE家族转录调节因子基因的同源臂序列，构建带有内部缺失LCAZH_0458基因的敲除载体。采用Cre/lox基因重组系统，筛选双交换子L. casei Zhang-G/A-1200/600-0458::lox66-P32-cat-lox71，构建突变株L. casei Zhang-G/A-1200/600_Δ0458。此外，作者通过稀释法研究了野生菌株和突变株的耐药表型。耐药表型结果表明，与野生菌株相比，突变株在庆大霉素质量浓度为8 ?滋g/mL和16 ?滋g/mL时，浊度提高约2倍。在阿莫西林环境下，浊度和活菌数均未发生改变。LCAZH_0458对干酪乳杆菌适应庆大霉素环境有一定的调节作用 。

Abstract:

In order to study the adaptive evolution mechanism of L. casei Zhang in antibiotic environment, the gene knockout system was constructed and the resistant phenotype of mutants was studied. The homologous arm sequence of the XRE family transcriptional regulator gene was amplified by PCR, and a knockout vector with internal deletion of LCAZH_0458 gene was constructed.Using the Cre/lox gene recombination system, the double-crossing L. casei Zhang-G/A-1200/600-0458:: lox66-P32-cat-lox71 was screened and the mutant strain L. casei Zhang-G/A-1200/600-Δ0458 was constructed. Besides, the antibiotic resistance phenotype of the wild strain and mutants were studied by the dilution method. The drug-resistant phenotypic results showed that the turbidity was increased by a factor of about 2 when the gentamicin concentrations were 8 μg/mL and 16 μg/mL compared to the wild strain. In the amoxicillin environment, there was no change in the turbidity and viable counts. LCAZH_0458 has a certain regulatory effect on the gentamicin environment of L. casei.