Isolation of Norfloxacin Resistant Bacteria and Analysis of Its Antibiotic Resistance Genes From the Wastewater Treatment System of a Livestock Farm

The accumulation and diffusion of antibiotic resistant bacteria and resistance genes in wastewater treatment systems of livestock farm poses potential hazards to ecological environment and human health. Therefore, it is necessary to investigate the types of resistant bacteria, resistance genes and genetic characteristics in the livestock wastewater treatment systems. In this study, a norfloxacin-resistant strain TY-1 was isolated from the sludge, which was collected from the secondary sedimentation tank of a meat goose farm in Jiangsu Province. The strain TY-1 was identified as Sphingomonas sp., according to the results of morphological, physiological and biochemical characteristics, and 16S rRNA gene sequence analysis. Based on the whole genome annotation of Sphingomonas sp., it was found that strain TY-1 had multiple antibiotic resistance genes (ARGs), including ABC transporter, MFS transporter and cytochrome P450 dehydrogenase. According to the results of gene cluster analysis, these ARGs were ubiquitous in genus of Sphingomonas. This study can provide a useful reference for the ecological risk assessment of pathogenic microorganisms containing antibiotic resistance genes in the wastewater treatment systems of livestock farm.