The Composition, Diversity and Predictive Metabolic Profiles of Bacteria Associated With the Gut Digesta of Five Sea Urchins in Luhuitou Fringing Reef (Northern South China Sea).

Sea urchins strongly affect reef ecology, and the bacteria associated with their gut digesta have not been well studied in coral reefs. In the current study, we analyze the bacterial composition of five sea urchin species collected from Luhuitou fringing reef, namely , , , , and , using high-throughput 16S rRNA gene-based pyrosequencing. , , and were found to be the dominant bacterial genera in all five species. Interestingly, four sea urchin species, including , , , and , displayed a higher mean total abundance of the three bacterial genera (69.72 ± 6.49%) than (43.37 ± 13.47%). Diversity analysis indicated that the gut digesta of sea urchin displayed a higher bacterial α-diversity compared with the other four species. PCoA showed that the four groups representing , , , and were overlapping, but distant from the group representing . Predictive metagenomics performed by PICRUSt revealed that the abundances of genes involved in amino acid metabolism and metabolism of terpenoid and polyketide were higher in , while those involved in carbohydrate metabolism were higher in the other four sea urchin species. Therefore, our results indicated that the composition, diversity and predictive metabolic profiles of bacteria associated with the gut digesta of were significantly different from those of the other four sea urchin species in Luhuitou fringing reef.