Chitinolytic bacteria in the intestinal tract of Japanese coastal fishes
Intestinal bacteria from several coastal fish species were screened on 1/20 PYBG medium containing 0.2% colloidal chitin, and 361 bacteria capable of decomposing colloidal chitin were isolated. These isolates were subsequently screened on media containing either 0.5% α-chitin or 0.5% β-chitin resulting in the identification of 31 α-chitinolytic and 275 β-chitinolytic bacterial isolates. Partial 16S rRNA gene sequencing was carried out and homology searches of the resultant sequences against the DDBJ, EMBL, and GenBank databases revealed that the majority (99%) of the chitinolytic bacteria isolated belonged to the Vibrionaceae. Phylogenetic analysis using a Bayesian approach showed that the α-chitinolytic bacteria belonging to the Vibrionaceae formed a separate cluster from the non-α-chitinolytic bacteria in the Vibrionaceae.Key words: chitinolytic bacteria, 16S rRNA, α-chitin, coastal fish, intestinal bacteria.