Plymouth Marine Laboratory, Plymouth, UK.
ISME J. 2010 Dec;4(12):1531-44. doi: 10.1038/ismej.2010.86. Epub 2010 Jul 1.
Bioturbation is a key process in coastal sediments, influencing microbially driven cycling of nutrients as well as the physical characteristics of the sediment. However, little is known about the distribution, diversity and function of the microbial communities that inhabit the burrows of infaunal macroorganisms. In this study, terminal-restriction fragment length polymorphism analysis was used to investigate variation in the structure of bacterial communities in sediment bioturbated by the burrowing shrimp Upogebia deltaura or Callianassa subterranea. Analyses of 229 sediment samples revealed significant differences between bacterial communities inhabiting shrimp burrows and those inhabiting ambient surface and subsurface sediments. Bacterial communities in burrows from both shrimp species were more similar to those in surface-ambient than subsurface-ambient sediment (R=0.258, P<0.001). The presence of shrimp was also associated with changes in bacterial community structure in surrounding surface sediment, when compared with sediments uninhabited by shrimp. Bacterial community structure varied with burrow depth, and also between individual burrows, suggesting that the shrimp's burrow construction, irrigation and maintenance behaviour affect the distribution of bacteria within shrimp burrows. Subsequent sequence analysis of bacterial 16S rRNA genes from surface sediments revealed differences in the relative abundance of bacterial taxa between shrimp-inhabited and uninhabited sediments; shrimp-inhabited sediment contained a higher proportion of proteobacterial sequences, including in particular a twofold increase in Gammaproteobacteria. Chao1 and ACE diversity estimates showed that taxon richness within surface bacterial communities in shrimp-inhabited sediment was at least threefold higher than that in uninhabited sediment. This study shows that bioturbation can result in significant structural and compositional changes in sediment bacterial communities, increasing bacterial diversity in surface sediments and resulting in distinct bacterial communities even at depth within the burrow. In an area of high macrofaunal abundance, this could lead to alterations in the microbial transformations of important nutrients at the sediment-water interface.
生物扰动是沿海沉积物中的一个关键过程，影响着微生物驱动的养分循环以及沉积物的物理特性。然而，对于栖息在底栖大型动物洞穴中的微生物群落的分布、多样性和功能知之甚少。在这项研究中，末端限制性片段长度多态性分析被用于研究掘穴虾（Upogebia deltaura 或 Callianassa subterranea）生物扰动沉积物中细菌群落结构的变化。对 229 个沉积物样本的分析表明，栖息在虾洞穴中的细菌群落与栖息在环境表面和亚表面沉积物中的细菌群落存在显著差异。两种虾的洞穴中的细菌群落与环境表面沉积物的相似性大于与亚表面环境沉积物的相似性（R=0.258，P<0.001）。与没有虾栖息的沉积物相比，虾的存在也与周围表面沉积物中细菌群落结构的变化有关。细菌群落结构随洞穴深度而变化，也在单个洞穴之间变化，这表明虾的洞穴建造、灌溉和维护行为影响了细菌在虾洞穴内的分布。随后对表面沉积物中细菌 16S rRNA 基因的序列分析表明，栖息虾和非栖息虾沉积物中细菌分类群的相对丰度存在差异；栖息虾沉积物中含有更高比例的变形菌门序列，特别是γ变形菌门的比例增加了两倍。Chao1 和 ACE 多样性估计表明，栖息虾沉积物中表面细菌群落的分类丰富度至少是无虾栖息沉积物的三倍。本研究表明，生物扰动会导致沉积物细菌群落发生显著的结构和组成变化，增加表面沉积物中的细菌多样性，并在洞穴内的深处形成独特的细菌群落。在一个大型动物丰度较高的区域，这可能会导致微生物对重要养分在沉积物-水界面的转化发生改变。
