J. Gen. Appl. Microbiol., 59, 1‒10 (2013)

Sea cucumbers are found in various sea environments like sea floors from the deep sea to intertidal areas (Foster and Hodgson, 1995; Uthicje et al., 2009). Sea cucumbers belong to the phylum Echinodermata and they mainly feed on detritus containing organic matter, microalgae, and bacteria (Massin, 1982; Moriarty, 1982; Yingst, 1976). Gut microorganisms are important for digestion of diets, but the relationships between host sea cucumbers and their gut bacteria and bacterial functions are not still clear. Studies on bacteria associated with sea cucumbers were reported only for Holothuria atra and Molpadia musculus (Amaro et al., 2009; Ward-Rainey et al., 1996). Ward-Rainey et al. reported preliminary research on aerobic bacterial flora of Holothuria atra. In their research, only 23 isolates were characterized by 16S rRNA gene sequence analysis (the first 300 nucleotides) and they were affiliated to the genera Vibrio and Bacillus. It was reported that the bacterial community of an abyssal holothurian, Molpadia musculus was analyzed using non-culturing methods (Amaro et al., J. Gen. Appl. Microbiol., 59, 1‒10 (2013)