Nithyanand Paramasivam, Pandian Shunmugiah Karutha
Department of Biotechnology, Alagappa University, Tamil Nadu 630 003, India.
FEMS Microbiol Ecol. 2009 Sep;69(3):384-94. doi: 10.1111/j.1574-6941.2009.00723.x. Epub 2009 Jun 11.
Corals, considered the rainforests of the oceans, harbour an abundance of different bacterial populations throughout the coral structure. In the present study we attempted to characterize the cultivable bacterial population associated within the mucus and tissue of the coral Acropora digitifera from the Gulf of Mannar. 16S rRNA gene was amplified from the cultured mucus and tissue isolates. Amplified ribosomal DNA restriction analysis, performed with a combination of restriction enzymes to determine the polymorphic groups of bacteria, generated 19 distinct groups in the coral mucus and 17 distinct groups in the coral tissue. Phylogenetic analyses based on the full-length sequences of 16S rRNA gene sequences showed that the majority of bacterial isolates belonged to the group Firmicutes, followed by Gammaproteobacteria and Actinobacteria. On investigating their antimicrobial activity, mucus isolates showed about 25% activity and tissue isolates showed 48% activity. This study revealed the presence of actinomycetes in both the coral mucus and the coral tissue, which had high activity against pathogens. This study, for the first time, demonstrates that actinomycetes existing within corals also have potential antibacterial activity. This has been overlooked so far, and indicates that, in addition to mucus, bacteria within the tissue of corals might defend the coral host against pathogens.
珊瑚被视为海洋中的热带雨林，在整个珊瑚结构中蕴藏着大量不同的细菌种群。在本研究中，我们试图对来自马纳尔湾的指状鹿角珊瑚的黏液和组织内可培养的细菌种群进行特征描述。从培养的黏液和组织分离物中扩增出16S rRNA基因。使用多种限制性内切酶组合进行扩增核糖体DNA限制性分析，以确定细菌的多态性群体，在珊瑚黏液中产生了19个不同的群体，在珊瑚组织中产生了17个不同的群体。基于16S rRNA基因序列全长进行的系统发育分析表明，大多数细菌分离物属于厚壁菌门，其次是γ-变形菌纲和放线菌门。在研究它们的抗菌活性时，黏液分离物显示出约25%的活性，组织分离物显示出48%的活性。这项研究揭示了在珊瑚黏液和珊瑚组织中均存在放线菌，它们对病原体具有高活性。本研究首次证明，存在于珊瑚内的放线菌也具有潜在的抗菌活性。这一点迄今一直被忽视，并且表明，除了黏液之外，珊瑚组织内的细菌也可能保护珊瑚宿主抵御病原体。
