Microbial Communities Associated with Holothurians: Presence of Unique Bacteria in the Coelomic Fluid

Abstract

Marine invertebrates interact with various microorganisms ranging from pathogens to symbionts. One-to-one symbiosis between a single microbial species and a single host animal has served as a model for the study of host-microbe interactions. In addition, increasing attention has recently been focused on the complex symbiotic associations, e.g. , associations between sponges and their symbionts, due to their biotechnological potential; however, relatively little is known about the microbial diversity associated with members of the phylum Echinodermata . Here, for the first time, we investigated microbial communities associated with a commercially important holothurian species, Apostichopus japonicus , using culture-dependent and -independent methods. Diverse and abundant heterotrophs, mostly Gammaproteobacteria members, were cultured semi-quantitatively. Using the cloning and sequencing technique, different microbial communities were found in different holothurian tissues. In the holothurian coelomic fluid, potentially metabolically active and phylogenetically unique members of Epsilonproteobacteria and Rickettsiales were discovered. This study suggests that coelomic fluids of marine invertebrates, at least those inhabiting intertidal areas where physical and chemical conditions fluctuate, provide microbes with unique and stable habitats.

Physiological characterization of aerobic culturable bacteria in the intestine of the sea cucumber Apostichopus japonicus

“…On the other hand, Enomoto et al reported that Gammaproteobacteria members including Vibrio spp. were isolated as culturable bacteria from the intestine of Apostichopus japonicus (Enomoto et al, 2012). It was reported that the frequency and level of Vibrio species were much lower during winter than summer months (Chowdhury et al, 1990;Colwell, 1979).…”

“…Recently Enomoto et al reported that Gammaproteobacteria members containing Vibrio spp. were isolated as culturable bacteria from the intestine of Apostichopus japonicus (Enomoto et al, 2012). Using molecular techniques, they also found that Proteobacteria members were main metabolically active microbial populations in the intestine of Apostichopus japonicus.…”

Diversity and function of aerobic culturable bacteria in the intestine of the sea cucumber Holothuria leucospilota

“…Enomoto et al report-ed that Gammaproteobacteria members were mainly isolated as culturable bacteria from the intestine of the Japanese spiky sea cucumber Apostichopus japonicus (Enomoto et al, 2012). Using molecular techniques, they also found that Proteobacteria members were the main metabolically active microbial populations in the intestine of A. japonicus.…”

Repeated selective enrichment process of sediment microbiota occurred in sea cucumber guts

“…In addition, Vibrionales known as facultative anaerobes and Desulfobacterales known as sulfate reducers were enriched in northern and southern sea cucumber guts respectively (Figs and ). Previous studies showed that Vibrionales is often dominant in sea cucumber guts (Enomoto et al ., ; Plotieau et al ., ; Gao et al ., ). These bacterial taxa cause fermentation within sea cucumber guts and may contribute to the decomposition of organic matter and further dissimilation processes in cooperation with other bacteria and host metabolism.…”