Deciphering Probiotic Effects of Sulfitobacter pontiacus Strain BL28 on the Host Sea Cucumber Apostichopus japonicus.

Recently, sea cucumber has been an increasingly important marine invertebrate in the fields of EcoDevo and fisheries studies. After the discovery of Sulfitobacter pontiacus strain BL28, which is a growth-promoting probiotic bacteria isolated from blastula of Apostichopus japonicus, host-microbes interaction has become a major new focus of study to be unveiled. Previous genome assessments of the strain BL28 hypothesized involvements of cobalamin/B12 biosynthesis, type IV secretion system, polyhydroxybutyrate production, and sulfate metabolism for host growth promotions. Here, we performed A. japonicus host transcriptome after five weeks of supplementation with S. pontiacus BL28. Unexpectedly, the host transcriptome revealed significant gene regulations of the BL28 supplementation on the host lipid and chondroitin metabolisms and transcriptionally "rest" status of heat shock protein genes un-expressed. Physiological and environmental crossover by the S. pontiacus BL28 supplementation may trigger stress-free growth promotion in the host sea cucumber. These symbiotics-type probiotics could help herald the future eco-friendly aquaculture of sea cucumber.