Description of Limnobaculum eriocheiris sp. nov., an intestinal bacterium of Eriocheir sinensis, and reclassification of the genera Jinshanibacter and Insectihabitans as Limnobaculum

Abstract

A Gram-stain-negative, aerobic, non-motile and rod-shaped strain, designated LJY008T, was isolated from the intestinal of Eriocheir sinensis in Pukou base of Jiangsu Institute of Freshwater Fisheries. Strain LJY008T could grow at 4-37℃ (optimum, 30℃), pH 6.0-8.0 (optimum, pH 7.0), and with 1.0-6.0% NaCl (w/v; optimum, 1.0%). Strain LJY008T shared highest 16S rRNA gene sequence similarity with Jinshanibacter zhutongyuii CF-458T (99.3%), followed by J. allomyrinae BWR-B9T (99.2%), Insectihabitans xujianqingii CF-1111T (97.3%), and Limnobaculum parvum HYN0051T (96.7%). The major polar lipids include phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol. The only respiratory quinone was Q8, and the main fatty acids (> 10%) were C16:0, summed feature 3 (C16:1ω7c/C16:1ω6c), summed feature 8 (C18:1ω7c), and C14:0. The genome-based phylogenies showed that strain LJY008T was closely associated with members of the genus Jinshanibacter, Insectihabitans, and Limnobaculum. The average nucleotide identities and average amino acid identities (AAI) among strain LJY008T and closely related neighbours were all below 95%, and the digital DNA-DNA hybridization values among them were all below 36%. The genomic DNA G + C content of strain LJY008T was 46.1%. Based on the phenotypic, phylogenetic, biochemical and chemotaxonomic analysis, strain LJY008T represents a novel species of the genus Limnobaculum, for which the name Limnobaculum eriocheiris sp. nov. is proposed. The type strain is LJY008T (= JCM 34675T = GDMCC 1.2436T = MCCC 1K06016T). In addition, the genera Jinshanibacter and Insectihabitans were reclassified as Limnobaculum, because there was no significant genome-scale divergence or diagnosable difference on phenotypic and chemotaxonomic traits, such as strains of Jinshanibacter and Insectihabitans sharing AAI values of 93.88-94.96%.