摘要
      盐度被认为是影响土壤中抗生素抗性基因（ARGs）分布的重要因素之一，因此其在形成抗生素抗性组中的作用仍知之甚少。在这里，进行了宏基因组分析，以跟踪盐积累和脱盐过程中ARGs在土壤中的分布和传播。中性盐积累45天和90天显著增加了携带抗生素抗性重叠群（ARC）的ARGs和移动遗传元件（MGE）的相对丰度。抗生素外排和靶标保护家族中的ARGs主要由链霉菌、类诺卡氏菌、Rhodanobacter和Monashia携带，主要因盐度而富集。耐药结瘤分裂（RND）家族、ATP结合盒（ABC）家族、rRNA甲基转移酶和其他外排的ARGs亚型与MGE密切相关，有助于ARGs的富集。此外，ARGs亚型和转座子与同一ARC上的有机渗透转运蛋白和K+摄取蛋白的耐盐机制存在遗传联系，表明ARGs和耐盐基因是共选择的。此外，通过缓解盐胁迫，抗生素耐药性可以在长时间培养后恢复到正常状态。尽管如此，盐处理后机会性病原体对ARGs的获取增加了，这有助于优先考虑进一步研究与耐药性传播和人类在盐碱地中暴露相关的健康风险。
Abstract
Salinity is considered as one of the vital factors affecting the profiles of antibiotic resistance genes (ARGs) in soils, whereby its roles in shaping the antibiotic resistome were still poorly understood. Here, metagenomic analysis was conducted to track the ARGs distributions and dissemination in soils during salt accumulation and desalinization processes. Neutral-salt accumulation for 45 and 90 days significantly increased the relative abundances of ARGs and mobile genetic elements (MGEs) carrying antibiotic resistance contigs (ARCs). The ARGs within antibiotic efflux and target protection families primarily carried by Streptomyces, Nocardioides, Rhodanobacter and Monashia were largely enriched by salinity. The ARGs subtypes of the resistance-nodulation-division (RND) family, ATP-binding cassette (ABC) family, rRNA methyltransferase and other efflux were closely associated with MGEs, contributing to the enrichment of ARGs. Moreover, the ARGs subtypes and transposons were genetically linked with the salt-tolerance mechanisms of organic osmolyte transporters and K+ uptake proteins on the same ARC, demonstrating the coselection of ARGs and halotolerant genes. Furthermore, the antibiotic resistome could recover to a normal state after the prolonged incubation by alleviating salt stress. Nevertheless, the acquisition of ARGs by opportunistic pathogens after salt treatment was increased, serving to prioritize further efforts on the health risks correlated with resistance propagation and human exposure in saline soils.

https://www.sciencedirect.com/science/article/abs/pii/S0269749122020450