Pesce Stéphane, Kergoat Laura, Paris Laurianne, Billet Loren, Besse-Hoggan Pascale, Bonnineau Chloé
Université Clermont Auvergne, CNRS, Institut de Chimie de Clermont-Ferrand, Clermont-Ferrand, France.
Université Clermont Auvergne, CNRS, Sigma Clermont, Institut de Chimie de Clermont-Ferrand, Clermont-Ferrand, France.
Front Microbiol. 2021 Nov 3;12:753647. doi: 10.3389/fmicb.2021.753647. eCollection 2021.
The sulfonamide antibiotics sulfamethoxazole (SMX) and sulfamethazine (SMZ) are regularly detected in surface sediments of contaminated hydrosystems, with maximum concentrations that can reach tens of μg kg in stream and river sediments. Little is known about the resulting effects on the exposed benthic organisms. Here we investigated the functional response of stream sediment microbial communities exposed for 4 weeks to two levels of environmentally relevant concentrations of SMX and SMZ, tested individually. To this end, we developed a laboratory channel experiment where natural stream sediments were immersed in water contaminated with nominal environmental concentrations of 500 and 5,000 ng L of SMX or SMZ, causing their accumulation in surface sediments. The mean maximum concentrations measured in the sediment (about 2.1 μg SMX kg dw and 4.5 μg SMZ kg dw) were consistent with those reported in contaminated rivers. The resulting chronic exposure had various effects on the functional potential of the sediment microbial communities, according to the substance (SMX or SMZ), the type of treatment (high or low) and the measured activity, with a strong influence of temporal dynamics. Whereas the SMZ treatments resulted in only transient effects on the five microbial activities investigated, we observed a significant stimulation of the β-glucosidase activity over the 28 days in the communities exposed to the high concentration of SMX. Together with the stimulation of aerobic respiration at low SMX concentrations and the reduced concentration observed in the last days, our results suggest a potential biodegradation of sulfonamides by microbial communities from sediments. Given the key functional role of surface sediment microbial communities in streams and rivers, our findings suggest that the frequently reported contamination of sediments by sulfonamides is likely to affect biogeochemical cycles, with possible impact on ecosystem functioning.
在受污染水系的表层沉积物中经常能检测到磺胺类抗生素磺胺甲恶唑（SMX）和磺胺二甲嘧啶（SMZ），在溪流和河流沉积物中的最大浓度可达数十微克/千克。关于其对暴露的底栖生物产生的影响，我们知之甚少。在此，我们研究了溪流沉积物微生物群落对两种与环境相关浓度的SMX和SMZ（单独测试）暴露4周后的功能响应。为此，我们开展了一项实验室渠道实验，将天然溪流沉积物浸入含有标称环境浓度为500和5000纳克/升的SMX或SMZ的污染水中，导致它们在表层沉积物中积累。沉积物中测得的平均最大浓度（约2.1微克SMX/千克干重和4.5微克SMZ/千克干重）与受污染河流中报道的浓度一致。根据物质（SMX或SMZ）、处理类型（高或低）和测量的活性，由此产生的慢性暴露对沉积物微生物群落的功能潜力有不同影响，且受时间动态的强烈影响。虽然SMZ处理对所研究的五种微生物活性仅产生短暂影响，但我们观察到在暴露于高浓度SMX的群落中，β-葡萄糖苷酶活性在28天内受到显著刺激。再加上低浓度SMX下对有氧呼吸的刺激以及最后几天观察到的浓度降低，我们的结果表明沉积物中的微生物群落可能对磺胺类药物进行生物降解。鉴于表层沉积物微生物群落在溪流和河流中的关键功能作用，我们的研究结果表明，经常报道的沉积物受磺胺类药物污染可能会影响生物地球化学循环，并可能对生态系统功能产生影响。
