Cardiff School of Biosciences, BIOSI 1, University of Cardiff, P.O. Box 915, Cardiff, Wales, CF10 3TL, UK.
Centre for Ecology and Hydrology, Maclean Building, Benson Lane, Wallingford, Oxfordshire, OX10 8BB, UK.
Environ Microbiol. 2015 Jun;17(6):1884-96. doi: 10.1111/1462-2920.12712. Epub 2014 Dec 17.
Earthworms are globally distributed and perform essential roles for soil health and microbial structure. We have investigated the effect of an anthropogenic contamination gradient on the bacterial community of the keystone ecological species Lumbricus rubellus through utilizing 16S rRNA pyrosequencing for the first time to establish the microbiome of the host and surrounding soil. The earthworm-associated microbiome differs from the surrounding environment which appears to be a result of both filtering and stimulation likely linked to the altered environment associated with the gut micro-habitat (neutral pH, anoxia and increased carbon substrates). We identified a core earthworm community comprising Proteobacteria (∼50%) and Actinobacteria (∼30%), with lower abundances of Bacteroidetes (∼6%) and Acidobacteria (∼3%). In addition to the known earthworm symbiont (Verminephrobacter sp.), we identified a potential host-associated Gammaproteobacteria species (Serratia sp.) that was absent from soil yet observed in most earthworms. Although a distinct bacterial community defines these earthworms, clear family- and species-level modification were observed along an arsenic and iron contamination gradient. Several taxa observed in uncontaminated control microbiomes are suppressed by metal/metalloid field exposure, including eradication of the hereto ubiquitously associated Verminephrobacter symbiont, which raises implications to its functional role in the earthworm microbiome.
蚯蚓在全球范围内分布广泛，对土壤健康和微生物结构起着至关重要的作用。我们首次利用 16S rRNA 焦磷酸测序技术研究了人为污染梯度对关键生态物种赤子爱胜蚓细菌群落的影响，以建立宿主及其周围土壤的微生物组。与周围环境相比，蚯蚓相关的微生物组有所不同，这似乎是由于过滤和刺激的双重作用，可能与肠道微生境（中性 pH 值、缺氧和增加的碳基质）改变有关。我们确定了一个由变形菌（约 50%）和放线菌（约 30%）组成的核心蚯蚓群落，拟杆菌门（约 6%）和酸杆菌门（约 3%）的丰度较低。除了已知的蚯蚓共生菌（Verminephrobacter sp.）外，我们还鉴定出一种潜在的与宿主相关的γ变形菌（Serratia sp.），它不存在于土壤中，但在大多数蚯蚓中都有观察到。尽管这些蚯蚓具有独特的细菌群落，但在砷和铁污染梯度上观察到了明显的科和种水平的修饰。在未受污染的对照微生物组中观察到的几个分类群由于金属/类金属的野外暴露而受到抑制，包括普遍存在的 Verminephrobacter 共生菌的根除，这对其在蚯蚓微生物组中的功能作用提出了影响。
