[Bacterial Diversity and Community Structure Antibiotic-resistant Bacteria in Bioaerosol of Animal Farms].

Confined animal feeding operations generate high concentrations of airborne antibiotic-resistant bacteria, including pathogenic strains that may pose a health risk to both animals and farm workers and pollute the local air environment. In this study, tetracycline and erythromycin-resistant bacteria were used as examples to study the biodiversity and community structure of airborne antibiotic-resistant bacteria in animal farms. The Anderson sampler was used to collect bioaerosols samples from the inside environment and outside atmospheric environments. A comparative analysis of biological differences of antibiotic-resistant bacteria was conducted on fine and coarse particles, bioaerosol samples inside the house, fecal samples, and inside and outside bioaerosol samples based on the result of the Illumina MiSeq sequencing. The key genus that drives the above differences was also studied. Results showed that the biodiversity of airborne erythromycin-resistant bacteria was higher than that of airborne tetracycline-resistant bacteria, and the biodiversity of bioaerosol samples in the house was higher than that in fecal samples. There were no significant differences in the biodiversity and community structure of airborne antibiotic-resistant bacteria between fine and coarse particles. Actinobacteria is one of the key bacteria responsible for the differences between erythromycin-resistant bacteria and other bacterial populations. Staphylococcus is one of the key genera of tetracycline-resistant flora that is distinguished from erythromycin resistance and all bacterial flora. The results of the community structure showed that there was no significant difference in the dominant flora and the community structure of tetracycline and erythromycin-resistant bacteria. The community structure of feces and bioaerosol samples is different at the genus level, and the dominant bacteria are likewise different. The results of this study provide basic data for the accurate assessment of the current status of antibiotic-resistant bacteria in animal farms and their ecological risks.

[Distribution Characteristics of Antibiotic Resistance Genes and Mobile Genetic Elements in Beijing Vegetable Base Soils].

The distribution characteristics of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) in five vegetable base soils from Beijing, China, were assessed. The composition of ARGs and MGEs in soil samples were analyzed by HT-qPCR. We detected 92-121 ARGs and 4-6 MGEs. The ARGs and MGEs in vegetable base soils from different districts were separated from each other. The dominant ARGs shared by vegetable bases were oprD, acrA-04, and acrA-05 of a multidrug, mphA-01 of MLSB, and ß-Lactamase fox5, vanC-03 of vancomycin. The shared MGE among the five vegetable base soils was intI1. A total of seven antibiotics were detected in the soil of several vegetable bases. The dominant antibiotics included enoxacin (ENR), norfloxacin (NOR), oxytetracycline (OTC), and sulfamethoxazole (SMX). The numbers and abundance of antibiotics in the soil of vegetable bases from the Shunyi district were the highest, followed by those from Tongzhou and Changping. Correlation analysis showed that there was a significant positive correlation between the abundance of ARGs and the abundance of antibiotics in the soil of vegetable bases (P<0.05). These results provide basic theoretical data for controlling the transmission of ARGs.

[Microbial Community Structure and the Distribution of Antibiotic Resistance Genes in Soil Contaminated by Sulfamethoxazole].

A pot experiment was carried out to simulate soil contaminated by sulfamethoxazole at different concentrations. The community structure of soil microorganisms was investigated using Illumina high-throughput sequencing, and 64 subtypes of antibiotic resistance genes (ARGs) resistant to six classes of antibiotic were also analyzed by PCR and droplet digital PCR. The results showed that soil contamination with sulfamethoxazole had no significant effect on fungal diversity after 120 days (P>0.05) whereas bacterial diversity was significantly reduced (P<0.05). The microbial community structure of the contaminated soil changed significantly, with the dominant bacterial and fungal genera being significantly different from the control soil. Sulfamethoxazole contamination resulted in an increase in ARG diversity, and the abundance of the sulfonamide resistance gene sul1 increased significantly (P<0.05). However, the abundance of the sulfonamide resistance gene sul2, the quinolone resistance genes floR and cmlA1, and the tetracycline resistance genes tet(34), tetG2, tetG1,tetM, and tetA/P did not show significant changes in the contaminated soil (P>0.05).