低浓度红霉素对猪链球菌蛋白表达、交叉耐药性与荚膜多糖的影响

Effects of low-concentration erythromycin on protein expression,cross resistance and capsular polysaccharides of Streptococcus suis

【目的】探索低浓度红霉素对猪链球菌蛋白表达、交叉耐药性与荚膜多糖的影响,为进一步研究饲料中低浓度抗生素促生长剂对环境中微生物的影响奠定基础。【方法】猪链球菌接触低浓度红霉素后,利用蛋白质组学iTRAQ技术,筛选关键差异表达蛋白。同时测定猪链球菌的交叉耐药性和荚膜多糖含量。【结果】共鉴定到差异表达蛋白181个,占总鉴定蛋白的12%,猪链球菌通过改变自身蛋白质组的表达量,以适应红霉素的选择性压力。多数差异表达蛋白参与催化和代谢过程,属于膜蛋白,其中13个ATP结合盒转运蛋白、3个核糖体蛋白、DNA回旋酶上调表达,8个荚膜多糖蛋白、DNA聚合酶Ⅳ下调表达。接触低浓度红霉素后,猪链球菌对多种抗生素出现交叉耐药性,消除红霉素后,药物敏感性恢复。接触低浓度红霉素后,荚膜多糖含量也未发生大幅度变化。【结论】猪链球菌为适应低浓度红霉素的选择性压力,大量表达多重耐药的主动外排泵,增加核糖体蛋白的表达量,降低荚膜多糖蛋白的表达量。

[Objective]To explore the effects of low-concentration erythromycin on protein expression,cross resistance and capsular polysaccharide of Streptococcus suis,so as to lay a foundation for further studying the effects of low-concentration antibiotic growth promoters in feed on microorganisms in the environment.[Methods]After S.suis was exposed to low-concentration erythromycin,key differentially expressed proteins were screened by iTRAQ.At the same time,we measured the cross resistance of S.suis and the content of capsular polysaccharide.[Results]A total of 181 differentially expressed proteins were identified,accounting for 12%of the total identified proteins.In order to adapt to the selective pressure of erythromycin,S.suis changed the expression of its own proteome.Most differentially expressed proteins were involved in catalytic and metabolic processes,and they belonged to membrane proteins.Among them,13 ATP-binding cassette transporters,3 ribosomal proteins and DNA gyrase were up-regulated,while 8 capsular polysaccharide proteins and DNA polymeraseⅣwere down-regulated.When S.suis was exposed to low-concentration erythromycin,it revealed cross resistance to a variety of antibiotics,whereas there was no significant change in the content of capsular polysaccharide.After elimination of erythromycin,the drug sensitivity recovered.[Conclusion]To adapt to the selective pressure of low-concentration erythromycin,S.suis up-regulated the expression of multidrug resistance efflux pumps to increase the levels of ribosomal protein and decrease the levels of capsular polysaccharide protein.