Taylor Michael W, Schupp Peter J, de Nys Rocky, Kjelleberg Staffan, Steinberg Peter D
School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
Environ Microbiol. 2005 Mar;7(3):419-33. doi: 10.1111/j.1462-2920.2004.00711.x.
Recent debate regarding microbial biogeography has focused largely on free-living microbes, yet those microbes associated with host organisms are also of interest from a biogeographical perspective. Marine eukaryotes and associated bacteria should provide ideal systems in which to consider microbial biogeography, as (i) bacteria in seawater should be able to disperse among individuals of the same host species, yet (ii) potential for adaptation to particular hosts (and thus speciation) also exists. We used 16S rDNA-DGGE (denaturing gradient gel electrophoresis) to examine geographic variability in bacterial community composition in the marine sponge Cymbastela concentrica. Denaturing gradient gel electrophoresis banding patterns (and phylogenetic analysis of excised DGGE bands) indicated different communities in Cymbastela concentrica from tropical versus temperate Australia. In contrast, communities were very similar over a 500-km portion of the sponge's temperate range. Variation in bacterial community composition was also considered with respect to ocean current patterns. We speculate that the divergent communities in different parts of the sponge's range provide evidence of endemism attributed to host association, although variation in environmental factors such as light and temperature could also explain the observed results. Interestingly, bacterial communities in seawater varied much less between tropical and temperate locations than did those in C. concentrica, supporting the concept of widespread dispersal among these free-living microbes.
最近关于微生物生物地理学的争论主要集中在自由生活的微生物上，然而从生物地理学的角度来看，那些与宿主生物相关的微生物也很有趣。海洋真核生物及其相关细菌应该能提供理想的系统来研究微生物生物地理学，因为（i）海水中的细菌应该能够在同一宿主物种的个体之间扩散，然而（ii）适应特定宿主（进而形成物种）的可能性也存在。我们使用16S rDNA - DGGE（变性梯度凝胶电泳）来研究海洋海绵同心柱星海绵（Cymbastela concentrica）中细菌群落组成的地理变异性。变性梯度凝胶电泳条带模式（以及对切下的DGGE条带进行的系统发育分析）表明，来自澳大利亚热带地区和温带地区的同心柱星海绵中的细菌群落不同。相比之下，在该海绵温带分布范围内500公里的区域内，群落非常相似。还结合洋流模式考虑了细菌群落组成的变化。我们推测，在该海绵分布的不同区域中存在差异的群落为宿主关联导致的特有现象提供了证据，尽管诸如光照和温度等环境因素的变化也可以解释所观察到的结果。有趣的是，海水细菌群落在热带和温带地区之间的差异远小于同心柱星海绵中的差异，这支持了这些自由生活微生物广泛扩散的概念。
