Chitinirhabdus sediminis gen. nov. sp. nov., a novel chitin-degrading bacterium of family Chitinibacteraceae isolated from the mangrove sediment

A novel bacterial strain with chitin-degrading ability, designated strain HSL-7^T, was isolated from a mangrove sediment in Guangxi, PR China. Cells of strain HSL-7^T were Gram-stain-positive, aerobic, rod-shaped bacteria with a single polar flagellum. The strain grew at concentrations of 0-1% (w/v) NaCl (optimum at 0.5%), at pH 6.0-10.0 (optimum at 7.0) and in a temperature range of 15-37 °C (optimum at 20 °C). Strain HSL-7^T shared the highest 16S rRNA gene sequence percentage with <i>Chitinibacter tainanensis</i> BCRC 17254^T (94.4%). Phylogenetic analyses based on 16S rRNA gene and genome sequences showed that strain HSL-7^T formed a distinct cluster in the family <i>Chitinibacteraceae</i>. The genome-relatedness indices between strain HSL-7^T and other type species of the family <i>Chitinibacteraceae</i> were in the ranges of 75.61-79.73% for average nucleotide identity, 65.50-70.65% for average amino acid identity and 12.7-17.4% for digital DNA-DNA hybridization, which were significantly below the cut-off values for the genus delineation. The genome comprised 3,144,197 bp with a genomic DNA G+C content of 61.5 mol%. The major isoprenoid quinone was ubiquinone-8. The predominant fatty acids were summed feature 3 (C_16:1 <i> </i>ω<i>6c</i> and/or C_16:1 <i> </i>ω<i>7c</i>), summed feature 8 (C_18:1 <i> </i>ω<i>7c</i> and/or C_18:1 <i> </i>ω<i>6c</i>) and C_16:0. The polar lipids comprised aminolipid, aminophospholipid, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phospholipid and an unidentified lipid. The polyphasic taxonomic properties indicated that the strain represents a novel genus and species in the family <i>Chitinibacteraceae</i> for which the name <i>Chitinirhabdus sediminis</i> gen. nov., sp. nov. is proposed. The type strain is HSL-7^T (=JCM 37906^T=MCCC 1K09933^T).