Chitinilyticum piscinae sp. nov., isolated from aquaculture water

A novel Gram-stain-negative and rod-shaped bacterial strain, designated as 4Y14^T, was isolated from aquaculture water and characterized by using a polyphasic taxonomic approach. Strain 4Y14^T was found to grow at 10-40 °C (optimum, 28 °C), at pH 7.0-9.0 (optimum, 7.0-8.0) and with 0-2 % NaCl (optimum, 1 %, w/v). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain 4Y14^T belonged to the genus Chitinilyticum with high levels of similarity to Chitinilyticum litopenaei c1^T (97.8 %) and Chitinilyticum aquatile c14^T (97.2 %). Phylogenomic analysis indicated that strain 4Y14^T formed an independent branch distinct from the two type strains above. Digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between strain 4Y14^T and the two type strains were, respectively, 25.3 and 25.0 %, and 81.2 and 80.3 %, which were well below the thresholds of 70 % DDH and 95-96 % ANI for species definition, implying that strain 4Y14^T should represent a novel genospecies. The predominant cellular fatty acids of strain 4Y14^T were summed feature 3 (C_16 : 1 ω7c and/or C_16 : 1 ω6c) and iso-C_16 : 0; the major polar lipids were diphosphatidylglycerol, phosphatidylcholine and phosphatidylethanolamine; and the sole respiratory quinone was Q-8. The genomic DNA G+C content was 60.1 mol%. Based on the phenotypic and genotypic analyses, strain 4Y14^T is concluded to represent a novel species of the genus Chitinilyticum, for which the name Chitinilyticum piscinae sp. nov. is proposed. The type strain of the species is 4Y14^T (=GDMCC 1.1934^T=KACC 22080^T).