环境细菌群落长期和反复暴露于人为抗生素最近促使一些抗生素抗性细菌获得分解代谢功能,使他们能够使用抗生素作为营养来源(抗生物营养)。抗生物营养可能具有选择性优势,有助于在污染环境中植入和分散抗生物营养物质。在农业生态系统背景下进行了微观实验以检验这一假设。磺酰胺降解和抗性细菌微杆菌属。在有和没有添加磺胺二甲嘧啶和/或猪粪的四种不同土壤类型中接种C448。孵化一个月后,微细菌。(及其抗生物营养基因sadA)仅在磺胺二甲嘧啶处理的土壤中检测到,表明在没有抗生素选择压力的情况下,菌株的竞争力较低。在没有粪肥的情况下,尽管存在微杆菌属。C448,四种磺胺二甲嘧啶处理的土壤中只有一种表现出矿化能力,低(低于5.5±0.3%)。相比之下,在所有土壤类型中添加粪肥显著增强了磺胺二甲基嘧啶的矿化(至少两倍,介于5.6±0.7%和19.5±1.2%之间)。这些结果,这证实了功能性基因的存在不一定能确保功能性,建议磺胺二甲嘧啶不一定赋予降解菌株作为营养来源的选择性优势。16SrDNA测序分析强烈表明,磺胺二甲嘧啶通过杀生物作用释放了营养生态位。因此,粪肥来源的细菌和/或微杆菌属。C448可以获得低竞争或无竞争的生态位。然而,粪肥和菌株的同时输入可能会诱导对微杆菌属有害的竞争。C448,迫使它使用磺胺二甲嘧啶作为营养来源。总之,这些结果表明,研究的抗生物营养菌株可以根据微生物竞争和资源可及性调节其磺胺二甲嘧啶降解功能,建立在农业土壤中。最重要的是,这项工作强调了抗生素污染环境中抗生物微生物的扩散潜力增加,因为抗生素不仅可以释放现有的营养生态位,还可以形成新的营养生态位。
Chronic and repeated exposure of environmental bacterial communities to anthropogenic antibiotics have recently driven some antibiotic-resistant bacteria to acquire catabolic functions, enabling them to use antibiotics as nutritive sources (antibiotrophy). Antibiotrophy might confer a selective advantage facilitating the implantation and dispersion of antibiotrophs in contaminated environments. A microcosm experiment was conducted to test this hypothesis in an agroecosystem context. The
sulfonamide-degrading and resistant bacterium Microbacterium sp. C448 was inoculated in four different soil types with and without added sulfamethazine and/or swine manure. After 1 month of incubation, Microbacterium sp. (and its antibiotrophic gene sadA) was detected only in the sulfamethazine-treated soils, suggesting a low competitiveness of the strain without antibiotic selection pressure. In the absence of manure and despite the presence of Microbacterium sp. C448, only one of the four sulfamethazine-treated soils exhibited mineralization capacities, which were low (inferior to 5.5 ± 0.3%). By contrast, manure addition significantly enhanced sulfamethazine mineralization in all the soil types (at least double, comprised between 5.6 ± 0.7% and 19.5 ± 1.2%). These results, which confirm that the presence of functional genes does not necessarily ensure functionality, suggest that sulfamethazine does not necessarily confer a selective advantage on the degrading strain as a nutritional source. 16S rDNA sequencing analyses strongly suggest that sulfamethazine released trophic niches by biocidal action. Accordingly, manure-originating bacteria and/or Microbacterium sp. C448 could gain access to low-competition or competition-free ecological niches. However, simultaneous inputs of manure and of the strain could induce competition detrimental for Microbacterium sp. C448, forcing it to use sulfamethazine as a nutritional source. Altogether, these results suggest that the antibiotrophic strain studied can modulate its sulfamethazine-degrading function depending on microbial competition and resource accessibility, to become established in an agricultural soil. Most importantly, this work highlights an increased dispersal potential of antibiotrophs in antibiotic-polluted environments, as antibiotics can not only release existing trophic niches but also form new ones.