Microbulbifer chitinilyticus sp. nov. and Microbulbifer okinawensis sp. nov., chitin-degrading bacteria isolated from mangrove forests

Abstract

Three chitin-degrading strains representing two novel species were isolated from mangrove forests in Okinawa, Japan. The isolates, ABABA23T, ABABA211 and ABABA212T, were Gram-negative, non-spore-forming, strictly aerobic chemo-organotrophs. The novel strains produced Q-8 as the major isoprenoid quinone component. The predominant fatty acids were iso-C15 : 0 and C16 : 0. On the basis of 16S rRNA gene sequence analysis, the isolates were closely affiliated with members of the genus Microbulbifer. The DNA G+C contents of strains ABABA23T and ABABA212T were 57.8 and 60.2 mol%, respectively. DNA–DNA relatedness values between these two strains and Microbulbifer reference strains were significantly lower than 70 %, the generally accepted threshold level below which strains are considered to belong to separate species. Based on differences in taxonomic characteristics, the three isolates represent two novel species of the genus Microbulbifer, for which the names Microbulbifer chitinilyticus sp. nov. (type strain, ABABA212T = JCM 16148T = NCIMB 14577T) and Microbulbifer okinawensis sp. nov. (type strain, ABABA23T = JCM 16147T = NCIMB 14576T; reference strain, ABABA211) are proposed.