摘要

金黄色葡萄球菌（Staphylococcus aureus）是形成生物膜的代表性食源性病原体之一。抗生素广泛应用于畜牧业以维持动物健康和生产力，从而有助于抗菌抗性家畜和人类病原体的传播，并构成重大的公共卫生威胁。抗生素压力对金黄色葡萄球菌生物膜形成的影响以及机制尚不清楚。在本研究中，阐明了低浓度氨苄青霉素对金黄色葡萄球菌生物膜形成的调节机制。通过XTT和结晶紫应变测定分别测定具有和不具有1/4 MIC氨苄青霉素处理8小时的生物膜的生存力和生物量。通过RNA测序，差异表达的基因鉴定和注释，GO功能和KEGG途径富集，对氨苄青霉素诱导的和非氨苄青霉素诱导的生物膜进行转录组学分析。与非氨苄青霉素诱导的生物膜相比，氨苄青霉素诱导的生物膜的活力和生物量显示出显着的增加。共获得530个差异表达基因（DEG），其中167和363个基因分别显示出上调和下调。在GO功能富集后，分别鉴定了生物过程，分子功能和细胞成分中的183,252和21个特定GO术语。包括“在不同环境中的微生物代谢”，“金黄色葡萄球菌感染”和“单体内部生物合成”的八种KEGG途径显着富集。此外，“β-内酰胺抗性”途径也高度富集。在氨苄青霉素诱导的生物膜中，编码多药耐药外排泵AbcA，青霉素结合蛋白PBP1，PBP1a / 2和PBP3以及抗菌耐药蛋白VraF，VraG，Dlt和Aur的基因的显着上调表明S的阳性反应金黄色葡萄球菌对氨苄西林。编码表面蛋白ClfB，IsdA和SasG以及促进金黄色葡萄球菌在氨苄青霉素诱导的生物膜中粘附的基因（cap5B和cap5C）的基因的上调可以解释增强的生物膜活力和生物量。

Staphylococcus aureus is one of the representative foodborne pathogens which forms biofilm. Antibiotics are widely applied in livestock husbandry to maintain animal health and productivity, thus contribute to the dissemination of antimicrobial resistant livestock and human pathogens, and pose a significant public health threat. Effect of antibiotic pressure on S. aureus biofilm formation, as well as the mechanism, remains unclear. In this study, the regulatory mechanism of low concentration of ampicillin on S. aureus biofilm formation was elucidated. The viability and biomass of biofilm with and without 1/4 MIC ampicillin treatment for 8 h were determined by XTT and crystal violet straining assays, respectively. Transcriptomics analysis on ampicillin-induced and non-ampicillin-induced biofilms were performed by RNA-sequencing, differentially expressed genes identification and annotation, GO functional and KEGG pathway enrichment. The viability and biomass of ampicillin-induced biofilm showed dramatical increase compared to the non-ampicillin-induced biofilm. A total of 530 differentially expressed genes (DEGs) with 167 and 363 genes showing up- and down-regulation, respectively, were obtained. Upon GO functional enrichment, 183, 252, and 21 specific GO terms in biological process, molecular function and cellular component were identified, respectively. Eight KEGG pathways including "Microbial metabolism in diverse environments", "S. aureus infection", and "Monobactam biosynthesis" were significantly enriched. In addition, "beta-lactam resistance" pathway was also highly enriched. In ampicillin-induced biofilm, the significant up-regulation of genes encoding multidrug resistance efflux pump AbcA, penicillin binding proteins PBP1, PBP1a/2, and PBP3, and antimicrobial resistance proteins VraF, VraG, Dlt, and Aur indicated the positive response of S. aureus to ampicillin. The up-regulation of genes encoding surface proteins ClfB, IsdA, and SasG and genes (cap5B and cap5C) which promote the adhesion of S. aureus in ampicillin induced biofilm might explain the enhanced biofilm viability and biomass.

https://www.ncbi.nlm.nih.gov/pubmed/30425687