Petroleum exploitation enriches the sulfonamide resistance gene sul2 in offshore sediments

Abstract

Antibiotic resistance genes (ARGs) have been considered as emerging contaminants in nature owing to their wide distribution and human health risk. Anthropogenic activities can increase the diversity and abundance of ARGs and promote their spread in environment. Offshore environment is affected by multiple types of anthropogenic activities, of which excessive accumulation of petroleum substances poses a serious threat. Our previous experimental study has demonstrated that petroleum can increase the abundance of sulfonamide resistance genes (SRGs) in the seawater through horizontal gene transfer. However, the influence of petroleum substances on SRGs in offshore environment, especially adjacent the petroleum exploitation platform, is still unclear. Therefore, the effect of offshore oil exploitation on SRGs was investigated in the surface sediments collected from the Liaodong Bay, north China. The genes of sul1 and sul2 were present in all of the collected samples, while the sul3 gene was not detected in any sediments. The absolute abundance of sul2 gene in each sample was higher than sul1 gene. Class 1 integrons enhanced the maintenance and propagation of sul1 gene but not sul2 gene. More importantly, the results indicate that the absolute abundance of sul2 gene present in the offshore sediments that affected by petroleum exploitation was significantly higher than those in control. These findings provided direct evidence that offshore oil exploitation can influence the propagation of SRGs and implied that a more comprehensive risk assessment of petroleum substances to public health risks should be conducted.