Centre for Marine Studies, The University of Queensland, Brisbane, Queensland, Australia.
PLoS One. 2010 Apr 29;5(4):e10401. doi: 10.1371/journal.pone.0010401.
Coral-associated bacteria are increasingly considered to be important in coral health, and altered bacterial community structures have been linked to both coral disease and bleaching. Despite this, assessments of bacterial communities on corals rarely apply sufficient replication to adequately describe the natural variability. Replicated data such as these are crucial in determining potential roles of bacteria on coral.
METHODOLOGY/PRINCIPAL FINDINGS: Denaturing Gradient Gel Electrophoresis (DGGE) of the V3 region of the 16S ribosomal DNA was used in a highly replicated approach to analyse bacterial communities on both healthy and diseased corals. Although site-specific variations in the bacterial communities of healthy corals were present, host species-specific bacterial associates within a distinct cluster of gamma-proteobacteria could be identified, which are potentially linked to coral health. Corals affected by "White Syndrome" (WS) underwent pronounced changes in their bacterial communities in comparison to healthy colonies. However, the community structure and bacterial ribotypes identified in diseased corals did not support the previously suggested theory of a bacterial pathogen as the causative agent of the syndrome.
CONCLUSIONS/SIGNIFICANCE: This is the first study to employ large numbers of replicated samples to assess the bacterial communities of healthy and diseased corals, and the first culture-independent assessment of bacterial communities on WS affected Acroporid corals on the GBR. Results indicate that a minimum of 6 replicate samples are required in order to draw inferences on species, spatial or health-related changes in community composition, as a set of clearly distinct bacterial community profiles exist in healthy corals. Coral bacterial communities may be both site and species specific. Furthermore, a cluster of gamma-proteobacterial ribotypes may represent a group of specific common coral and marine invertebrate associates. Finally, the results did not support the contention that a single bacterial pathogen may be the causative agent of WS Acroporids on the GBR.
珊瑚相关细菌在珊瑚健康中越来越被认为是重要的，改变的细菌群落结构与珊瑚疾病和白化有关。尽管如此，对珊瑚上细菌群落的评估很少进行足够的复制，以充分描述自然变异。这样的重复数据对于确定细菌对珊瑚的潜在作用至关重要。
方法/主要发现：使用变性梯度凝胶电泳（DGGE）对 16S 核糖体 DNA 的 V3 区进行分析，采用高度重复的方法分析健康和患病珊瑚上的细菌群落。尽管健康珊瑚的细菌群落存在特定地点的变异，但在一个特定的γ-变形菌簇内可以识别出宿主物种特异性的细菌伴生物，这些伴生物可能与珊瑚的健康有关。与“白色综合征”（WS）相关的珊瑚与健康珊瑚相比，其细菌群落发生了明显的变化。然而，在患病珊瑚中鉴定出的群落结构和细菌核糖体类型并不支持先前提出的细菌病原体是该综合征致病因子的理论。
结论/意义：这是第一项采用大量重复样本评估健康和患病珊瑚细菌群落的研究，也是首次对大堡礁 WS 受影响的鹿角珊瑚进行独立于培养的细菌群落评估。结果表明，为了推断物种、空间或与健康相关的群落组成变化，至少需要 6 个重复样本，因为在健康珊瑚中存在一组明显不同的细菌群落图谱。珊瑚细菌群落可能具有特定的地点和物种特异性。此外，一组γ-变形菌核糖体类型可能代表一组特定的常见珊瑚和海洋无脊椎动物伴生物。最后，结果不支持单一细菌病原体可能是大堡礁 WS 鹿角珊瑚的致病因子的说法。
