School of Biological Sciences, The University of Auckland, Auckland, New Zealand.
ISME J. 2010 Apr;4(4):498-508. doi: 10.1038/ismej.2009.143. Epub 2010 Jan 7.
The phylogenetic diversity of microorganisms in marine sponges is becoming increasingly well described, yet relatively little is known about the activities of these symbionts. Given the seemingly favourable environment provided to microbes by their sponge hosts, as indicated by the extraordinarily high abundance of sponge symbionts, we hypothesized that the majority of sponge-associated bacteria are active in situ. To test this hypothesis we compared, for the first time in sponges, 16S rRNA gene- vs 16S rRNA-derived bacterial community profiles to gain insights into symbiont composition and activity, respectively. Clone libraries revealed a highly diverse bacterial community in Ancorina alata, and a much lower diversity in Polymastia sp., which were identified by electron microscopy as a high- and a low-microbial abundance sponge, respectively. Substantial overlap between DNA and RNA libraries was evident at both phylum and phylotype levels, indicating in situ activity for a large fraction of sponge-associated bacteria. This active fraction included uncultivated, sponge-specific lineages within, for example, Actinobacteria, Chloroflexi and Gemmatimonadetes. This study shows the potential of RNA vs DNA comparisons based on the 16S rRNA gene to provide insights into the activity of sponge-associated microorganisms.
海洋海绵体中微生物的系统发生多样性的描述越来越完善，但人们对这些共生体的活动却知之甚少。考虑到海绵宿主为微生物提供的环境似乎非常有利，这从海绵共生体极高的丰度中可以看出，我们假设大多数海绵相关细菌都是原位活跃的。为了验证这一假设，我们首次在海绵体中比较了 16S rRNA 基因与 16S rRNA 衍生的细菌群落图谱，分别深入了解共生体的组成和活性。克隆文库揭示了 Ancorina alata 中高度多样化的细菌群落，而在 Polymastia sp. 中则多样性较低，电子显微镜鉴定分别为高微生物丰度和低微生物丰度的海绵。在门和菌型水平上，DNA 和 RNA 文库之间存在大量重叠，表明大部分海绵相关细菌具有原位活性。这个活跃的部分包括了放线菌门、绿弯菌门和芽单胞菌门等未培养的、具有海绵特异性的谱系。这项研究表明，基于 16S rRNA 的 RNA 与 DNA 比较有潜力为了解海绵相关微生物的活性提供见解。
