Bacterial diversity of gut content in sea cucumber (Apostichopus japonicus) and its habitat surface sediment

This study investigated the bacterial diversity of gut content of sea cucumber (Apostichopus japonicus) and its habitat surface sediment in a bottom enhancement area using PCR-based denaturing gradient gel electrophoresis (DGGE) technique. Bacterial diversity evaluation showed that the value of the Shannon-Wiener index of gut content in different intestinal segments of A. japonicus varied between 2.88 and 3.00, lower than that of the surrounding sediment (3.23). Phylogenetic analysis showed that bacterial phylotypes in gut content and the surrounding sediment of A. japonicus were closely related to Proteobacteria including gamma-, alpha-, delta- and E >-proteobacteria, Bacteroidetes, Firmicute, and Actinobacteria, of which gamma-proteobacteria were predominant. These results suggested that the sea cucumber A. japonicus was capable of feeding selectively, and PCR-DGGE was applicable for characterizing the bacterial community composition in gut content and the surrounding sediment of sea cucumber. Further investigation targeting longer 16S rDNA gene fragments and/or functional genes was recommended for obtaining more information of the diversity and function of bacterial community in the gut content of sea cucumber.