Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN, USA; BioTechnology Institute, University of Minnesota, St. Paul, MN, USA.
Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN, USA.
Sci Total Environ. 2020 Jul 10;725:138356. doi: 10.1016/j.scitotenv.2020.138356. Epub 2020 Apr 4.
Capitella teleta is a marine sediment-feeding polychaete known to degrade various polycyclic aromatic hydrocarbons (PAHs) and reported to possess genes involved in PAH transformation, such as those in the P450 cytochrome superfamily. Previous research focusing on biodegradation of PAHs by C. teleta demonstrated that these worms are effective biodegraders, but overlooked the possible role of its gut microbiota in facilitating PAH metabolism. Recently, C. teleta's microbiome was characterized and found to contain several bacterial genera known to contain PAH-degrading members, including Acinetobacter, Thalassotalea, and Achromobacter. Despite this, however, no data have thus far been presented demonstrating the role of C. teleta's gut microbiota in PAH degradation. The present study was designed to more conclusively determine the presence of PAH-degrading bacteria in worm digestive tracts and to more clearly distinguish the relative roles of worm versus gut-microbial metabolism in the removal of PAH from sediment. To do this, we manipulated marine sediment microorganisms and worm gut microbiota by autoclaving and antibiotic treatment, respectively. Our results showed that no fluoranthene degradation occurred in microcosms in the absence of worms. More importantly, there was no significant difference in fluoranthene degradation between antibiotic-treated and non-treated worms. We also found no evidence of fluoranthene degradation using resting cells of gut microbes of C. teleta, and we were unable to isolate fluoranthene-degrading bacterial strains from enrichments of polychaete gut contents, despite multiple attempts. Gut microbiota in worms treated with antibiotics recovered, through bidirectional transfer, between worms and sediment after 2 weeks of microcosm incubation, and gut microbes appear to be required for the survival and growth of C. teleta. Our results build on previous studies suggesting that C. teleta itself is primarily responsible for the metabolism of fluoranthene in ingested sediment. We hypothesize that C. teleta's core microbiota, which includes members of Propionibacterium as the most abundant genus, likely aid worms in obtaining key nutrients (e.g., vitamins) from its sediment diet.
被毛盘管虫是一种海洋沉积物食性多毛类动物，已知能降解各种多环芳烃（PAHs），并报告其拥有参与 PAH 转化的基因，如 P450 细胞色素超家族的基因。以前的研究集中在被毛盘管虫对 PAHs 的生物降解上，表明这些蠕虫是有效的生物降解剂，但忽略了其肠道微生物群在促进 PAH 代谢中的可能作用。最近，被毛盘管虫的微生物组被描述出来，发现其中包含几个已知含有 PAH 降解成员的细菌属，包括不动杆菌、海洋盐单胞菌和无色杆菌。尽管如此，迄今为止还没有数据表明被毛盘管虫的肠道微生物群在 PAH 降解中的作用。本研究旨在更明确地确定蠕虫消化道中存在的 PAH 降解细菌，并更清楚地区分蠕虫与肠道微生物代谢在从沉积物中去除 PAH 方面的相对作用。为此，我们分别通过高压灭菌和抗生素处理来操纵海洋沉积物微生物和蠕虫肠道微生物群。我们的结果表明，在没有蠕虫的情况下，微宇宙中没有发生荧蒽降解。更重要的是，抗生素处理和未处理的蠕虫之间在荧蒽降解方面没有显著差异。我们还发现，使用被毛盘管虫肠道微生物的静止细胞没有荧蒽降解的证据，尽管多次尝试，我们也无法从多毛类动物肠道内容物的富集物中分离出荧蒽降解细菌菌株。用抗生素处理的蠕虫的肠道微生物群在微宇宙孵育 2 周后通过双向转移在蠕虫和沉积物之间恢复，并且肠道微生物似乎是被毛盘管虫生存和生长所必需的。我们的研究结果建立在先前的研究基础上，表明被毛盘管虫本身主要负责摄入沉积物中荧蒽的代谢。我们假设被毛盘管虫的核心微生物群，其中包括丙酸杆菌属作为最丰富的属的成员，可能有助于蠕虫从其沉积物饮食中获得关键营养素（例如，维生素）。
