东寨港红树林典型区域氯霉素抗性基因的分布

Distribution of Chloramphenicol Resistance Genes in the Typical Area of Mangroves in Dongzhai Harbor,Hainan,China

采用实时荧光定量PCR方法,于2017年8月采集东寨港红树林区域表层沉积物,探究氯霉素抗性基因在该区域的污染情况,同时比较红树区域密林内与密林外沉积物样品中氯霉素抗性基因的分布差异及其与环境因子之间的相关性。结果表明:该区域受氯霉素抗性基因污染严重,基因绝对丰度可高达108 copies·g-1数量级;具有不同耐药机制的氯霉素抗性基因在环境样本中具有不同的组成比例,始终以cml基因居多,证明该地区的氯霉素抗性基因的耐药机制以抗生素主动外排为主;红树林密林内的沉积物样品中氯霉素抗性基因的绝对丰度比其他样点高;氯霉素抗性基因与环境因子的相关性分析显示亚硝酸盐(NO2--N)和氯霉素抗性基因具有极显著相关性。

The long-term abuse of antibiotics has led to the rapid growth of drug-resistant bacteria in the environment. The distribution and mechanism of antibiotics resistance genes（ ARGs） have attracted public attention.ARGs,as an emerging contaminant,not only have a serious impact on the environment,but also pose a potential threat to the health of organisms and human beings. The surface sediment of the mangrove area in Dongzhai Harbor,Haikou,Hainan,China was collected in the mangroves,near the mangroves and the mud flats in August,2017 to determine the abundance of ARGs by using real-time quantitative PCR in a view to investigate the pollution of chloramphenicol resistance genes（ CRGs） in this area. The distribution of CRGs in the sediment samples in the mangroves,near the mangroves and in the mud flats was analyzed and compared,and the correlation between the CRGs and the environmental factors were analyzed. The results showed that this area was seriously polluted by CRGs,with an absolute abundance of CRGs being 108 copies · g-1. CRGs with different resistance mechanisms had different compositional ratios in the environmental samples,of which the cml gene was always the highest in the compositional ratios of all the samples,indicating that the resistant mechanism of CRGs is based on active efflux of antibiotics. The sediment samples in the mangroves showed higher absolute abundance of CRGs than those near the mangroves or in the mud flats. Correlation analysis between the CRGs and the environmental factors showed that NO-2-N was highly significantly correlated with the CRGs.