头孢噻肟处理的城市河流沉积物微生物群落结构及bla_(CTX-M)多样性的研究

Diversity changes of the microbial communities and blaCTX-M genes in urban river sediments treated with cefotaxime

目的研究抗生素(头孢噻肟)作用下河流沉积物微生物群落结构的变化及耐药基因blaCTX-M多样性。方法应用基于16SrRNA的末端限制性酶切片段长度多态性(T-RFLP)技术,分析分别在0、6.4、64和320mg的头孢噻肟作用下,城市河流底泥细菌群落结构变化;并通过巢式PCR,分析其耐药基因blaCTX-M的多样性变化。结果T-RF特征峰统计分析表明:不同抗生素浓度处理,与底泥细菌群落结构多样性变化之间无显著相关性;但实验室处理时间会导致群落结构产生显著变化。PCR结果表明:随实验室处理时间的延长,耐药基因blaCTX-M多样性下降。结论对已承受排放废水污染的河流沉积物,由于其中富含大量的耐药菌群,其总体菌群结构对抗生素的作用不敏感。同时,对非原位开展的菌群结构研究,实验室处理时间是重要的影响因素。

Objective To explore the diversity changes of microbial communities and blaCTX-M in an urban river sediment community with cefotaxime treatment. Methods The terminal restriction fragment length polymorphism （T-RFLP） of 16S rDNA was employed to analyze the bacteria community, and the blaCTX-M was determined using nested PCR. The sediment was treated by cefotaxime at the concentrations of 0, 6.4, 64, and 320 mg/L. Results According to statistical analysis of the T-RFs, no significant correlation was observed between the antibiotic treatment and the microbial community change, but incubation in laboratory conditions had significant effect on the microbial diversity. The PCR results showed that the diversity of blaCTX-M decreased after the laboratory incubation. Conclusion As there are diverse antibiotic resistant bacteria in the sediments with prior pollution by antibiotics, the whole community can be inert to the antibiotic treatment. Nevertheless, the ex situ treatment conditions in laboratory studies have a significant impact on the community structures.