摘要
目的：肠毒素sek基因在临床分离的耐甲氧西林金黄色葡萄球菌菌株中较为流行,研究新型肠毒素sek基因的时序性表达可为食物中毒预防和疾病控制补充新的基础数据。方法：本研究针对实验室保存的食源性金黄色葡萄球菌菌株进行21种肠毒素基因检测,筛选出3株含sek基因的菌株SA005、SA008和SAB0,针对3株菌株进行生长曲线测定,随后在培养不同时间段收集菌体提取RNA,利用实时荧光定量聚合酶链式反应（real time-polymerase chain reaction,real time-PCR）检测肠毒素sek基因在12~120 h的相对表达水平。结果：基因检测结果显示,菌株SA005含有16S、nuc、mec A、seb、sec、sek、sex基因,SA008含有16S、nuc、mec A、sea、sek、sex基因,SAB0含有16S、nuc、sek、sex基因。3株菌株在胰酪胨大豆肉汤培养基中的生长曲线趋势较相似,18 h左右出现折点,之后细菌进入生长稳定期。3株菌株的sek基因在12~120 h全程表达,SA005的sek基因在48 h时相对表达量最高,在84 h相对表达量最低;SA008在24 h时的相对表达量最高,在48 h相对表达量最低,在60~120 h表达量相对比较稳定;SAB0在12~120 h之间相对表达量呈现抛物线趋势,在60 h和72 h的表达量相对较高且差异不显著（P〉0.05）。结论：3株菌株sek表达水平存在明显差异,相同菌株sek基因不同时间点表达也存在差异性,菌株基因背景的影响可能是造成sek基因表达差异性的关键。
Objective： The newly identified staphylococcal enterotoxin sek gene is found to be very popular in clinicalmethicillin-resistant S. aureus isolates. The study of sek gene temporal expression would provide some valuable informationand new data for food poisoning prevention and disease control linked to this bacterium. Methods： Three strains（SA005,SA008 and SAB0） with sek gene from foodborne isolates in our lab were selected by PCR detection of 21 different SEsgenes. The growth curves of three strains were monitored during the growth phase in TSB. Total RNAs from three strainswere extracted at different growth periods, and a quantitative real time-PCR was developed to monitor the relative expressionof sek gene. Results： The results of virulence gene detection showed that SA005 harbored 16 S, nuc, mec A, seb, sec, sek andsex genes, SA008 harbored 16 S, nuc, mec A, sea, sek and sex genes, and SAB0 harbored 16 S, nuc, sek and sex genes. Thecharacteristics of growth curves for three strains had similarity, which exhibited a turning point around 18 h, and then enteredthe stationary growth phase. m RNA expression levels were shown during all the growth phases（12–120 h）; however, therewere very obvious differences among three strains and among different sampling points. The relative expression of sek genewas very high at 48 h and very low at 84 h for SA005. For SA008, it was very high at 24 h, very low at 48 h, and was stablebetween 60–120 h. The relative expression of sek gene in SAB0 presented a parabolic trend, with a high level at 60 h and72 h（P〉0.05）. Conclusion： The relative expression of sek gene among three strains had a significant difference. Even in thesame strain, the relative expression of sek gene was different at different time points. Strain-to-strain variations with differentbackground genes may be the key points for different expression patterns of sek gene.
出处
《食品科学》
EI
CAS
CSCD
北大核心
2016年第13期140-146,共7页
Food Science
基金
国家自然科学基金面上项目(31371781)
四川省应用基础研究计划项目(14JC0702)
教育部"新世纪优秀人才支持计划"项目(NCET-11-0847)
