Steroids originating from bacterial bile acid degradation affect Caenorhabditis elegans and indicate potential risks for the fauna of manured soils
Steroids originating from bacterial bile acid degradation affect Caenorhabditis elegans and indicate potential risks for the fauna of manured soils
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DOI：
10.1038/s41598-019-47476-y
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发表时间：
2019-07-31
影响因子：
4.6
通讯作者：
Philipp, B.
中科院分区：
文献类型：
--
作者：
Mendelski, M. N.;Doelling, R.;Philipp, B.
胆汁酸是来自脊椎动物消化道的类固醇化合物，其以异常高的量随粪肥进入农业环境。降解胆汁酸的细菌可以容易地从土壤和沃茨（包括农业区）中分离。在实验室条件下，这些细菌瞬时释放类固醇化合物作为降解中间体进入环境。这些化合物包括雄甾二烯二酮（ADDs），其是具有潜在激素作用的C-19类固醇。对秀丽隐杆线虫的实验表明，细菌胆汁酸降解产生的ADDs影响其触觉反应、繁殖率和发育速度。用缺失突变体进行的其他实验以及转录组学分析表明，这些作用可能由推定的睾酮受体NHR-69传递。土壤微宇宙表明，农业土壤的天然微生物区系很容易诱导胆汁酸降解伴随着类固醇中间体的瞬时释放。建立了假单胞菌与C.沙区微宇宙中的线虫表明，在胆汁酸降解过程中，ADDs会短暂释放，并对线虫的繁殖率产生负面影响。这项原理验证研究指出，细菌降解粪便衍生的胆汁酸是农业土壤中无脊椎动物的一种潜在风险，迄今为止一直被忽视。
Bile acids are steroid compounds from the digestive tracts of vertebrates that enter agricultural environments in unusual high amounts with manure. Bacteria degrading bile acids can readily be isolated from soils and waters including agricultural areas. Under laboratory conditions, these bacteria transiently release steroid compounds as degradation intermediates into the environment. These compounds include androstadienediones (ADDs), which are C-19-steroids with potential hormonal effects. Experiments with Caenorhabditis elegans showed that ADDs derived from bacterial bile acid degradation had effects on its tactile response, reproduction rate, and developmental speed. Additional experiments with a deletion mutant as well as transcriptomic analyses indicated that these effects might be conveyed by the putative testosterone receptor NHR-69. Soil microcosms showed that the natural microflora of agricultural soil is readily induced for bile acid degradation accompanied by the transient release of steroid intermediates. Establishment of a model system with a Pseudomonas strain and C. elegans in sand microcosms indicated transient release of ADDs during the course of bile acid degradation and negative effects on the reproduction rate of the nematode. This proof-of-principle study points at bacterial degradation of manure-derived bile acids as a potential and so-far overlooked risk for invertebrates in agricultural soils.