Diversity and function of aerobic culturable bacteria in the intestine of deep-sea holothurian

Ninety-two aerobic culturable bacterial strains were isolated from each part of the intestine of the deep-sea holothurian collected at 32°30′N, 129°09′E (southeast of Fukue Island, Nagasaki, Japan) and water depth of 236 m in November 2010. The temperature of seawater at the water depth of the sampling point was estimated to be ca.13-14 °C from data in Japan Meteorological Agency. By partial 16S rRNA gene sequences of the isolates, the isolates belonged to 45 nearest type strain species (below, referred to as species). High diversity was observed in the genera Bacillus (21 species) and Vibrio (6 species). The bacterial diversity was similar among three parts, i.e. anterior, mid and posterior parts of the intestine and 14 species were detected in multiple parts of the intestine. Most isolates showed various polysaccharide degradation activities but few isolates showed alginate or agar degradation activities probably because there were no seaweeds containing alginate or agar in this deep-sea. Comparing the functions and properties of several species in three parts, the posterior part was likely to be different from the anterior or mid parts