Michigan Water Science Center, U.S. Geological Survey, Lansing, Michigan, USA.
Environ Sci Technol. 2012 Jul 17;46(14):7478-86. doi: 10.1021/es3009776. Epub 2012 Jun 29.
Effects upon microbial communities from environmental exposure to concentrations of antibiotics in the μg L(-1) range remain poorly understood. Microbial communities from an oligotrophic aquifer (estimated doubling rates of only once per week) that were previously acclimated (AC) or unacclimated (UAC) to historical sulfamethoxazole (SMX) contamination, and a laboratory-grown Pseudomonas stutzeri strain, were exposed to 240-520 μg L(-1) SMX for 30 days in situ using filter chambers allowing exposure to ambient groundwater, but not to ambient microorganisms. SMX-exposed UAC bacterial communities displayed the greatest mortality and impairment (viable stain assays), the greatest change in sensitivity to SMX (dose-response assays), and the greatest change in community composition (Terminal Restriction Fragment Length Polymorphism; T-RFLP). The sul1 gene, encoding resistance to SMX at clinically relevant levels, and an element of Class I integrons, was not detected in any community. Changes in microbial community structure and SMX resistance over a short experimental period in previously nonexposed, slow-growing aquifer communities suggest concentrations of antibiotics 2-3 orders of magnitude less than those used in clinical applications may influence ecological function through changes in community composition, and could promote antibiotic resistance through selection of naturally resistant bacteria.
环境暴露于μg/L 浓度抗生素对微生物群落的影响仍知之甚少。从贫营养含水层（估计每周仅倍增一次）中分离出的微生物群落，先前已经适应（AC）或未适应（UAC）历史上的磺胺甲恶唑（SMX）污染，以及实验室生长的恶臭假单胞菌菌株，使用允许暴露于环境地下水但不暴露于环境微生物的过滤室原位暴露于 240-520μg/L SMX 30 天。暴露于 SMX 的 UAC 细菌群落显示出最大的死亡率和损伤（可存活染色试验）、对 SMX 的最大敏感性变化（剂量反应试验）以及群落组成的最大变化（末端限制性片段长度多态性；T-RFLP）。在任何群落中都未检测到编码对临床相关水平的 SMX 耐药性的 sul1 基因和 I 类整合子的元件。在以前未暴露于低浓度、生长缓慢的含水层群落中，微生物群落结构和 SMX 抗性在短时间的实验期间发生变化，这表明抗生素浓度可能通过群落组成的变化影响生态功能，并且可以通过选择自然耐药菌来促进抗生素耐药性。
