海洋所演講公告 11月29日(三) 13：30 Endolithic green sulfur bacteria in the coral Isopora palifera. 楊姍樺 博士 (中央研究院生物多樣性中心)
講者：楊姍樺 博士 (中央研究院生物多樣性中心)
題目：Endolithic green sulfur bacteria in the coral Isopora palifera.
Microbial endoliths, which inhabit interior pores of rocks, skeletons and coral, are ubiquitous in terrestrial and marine environments.
In the present study, various colored layers stratified the endolithic environment within the skeleton of Isopora palifera; however, there was usually a distinct green-pigmented layer in the skeleton beneath the living coral tissue. To characterize diversity of endolithic microorganisms, 16S ribosomal RNA gene amplicon pyrosequencing was used to investigate bacterial communities in the green layer of I. palifera coral colonies retrieved from Lyudao (Green Island), Taiwan. The result showed that the dominant bacteria in the green layer belonged to the bacterial phylum Chlorobi, green sulfur bacteria capable of anoxygenic photosynthesis and nitrogen fixation.
Specifically, genus Prosthecochloris were prevalent in this green layer in the most coral colonies regardless of the difference of location and depth, suggesting versatile abilities in Prosthecochloris to accommodate different conditions. Moreover, using a metagenomics approach, nitrogen, sulfur and carbon cycles of the endolithic bacteria within the green layer was displayed, indicating the green sulfur bacteria is essential in nitrogen fixation, sulfur oxidation and carbon fixation. To our knowledge, this is the first study to provide a detailed profile of endolithic bacteria in coral skeleton, as well as, to determine their functions in nitrogen metabolism in this habitat. Based on our findings, we infer that these bacteria may have an important functional role in the coral holobiont in the nutrient-limited coral reef ecosystem.