Microbulbifer mangrovi sp. nov., a polysaccharide-degrading bacterium isolated from an Indian mangrove

Abstract

A rod-shaped, Gram-negative, non-motile, aerobic and non-endospore forming bacterium, designated strain DD-13(T), was isolated from the mangrove ecosystem of Goa, India. Strain DD-13(T) degraded polysaccharides such as agar, alginate, chitin, cellulose, laminarin, pectin, pullulan, starch, carrageenan, xylan and β-glucan. The optimum pH and temperature for growth was 7 and 36 °C, respectively. The strain grew optimally in the presence of 3 % NaCl (w/v). The DNA G+C content was 61.4 mol%. The predominant fatty acid of strain DD-13(T) was iso-C15 : 0. Ubiquinone-8 was detected as the major respiratory lipoquinone. Phylogenetic studies based on 16S rRNA gene sequence analysis demonstrated that strain DD-13(T) formed a coherent cluster with species of the genus Microbulbifer. Strain DD-13(T) exhibited 16S rRNA gene sequence similarity levels of 98.9-97.1 % with Microbulbifer hydrolyticus IRE-31(T), Microbulbifer salipaludis JCM 11542(T), Microbulbifer agarilyticus JAMB A3(T), Microbulbifer celer KCTC 12973(T) and Microbulbifer elongatus DSM 6810(T). However, the level of DNA-DNA relatedness between strain DD-13(T) and the five type strains of these species of the genus Microbulbifer were in the range of 26-33 %. Additionally, strain DD-13(T) demonstrates several phenotypic differences from these type strains of species of the genus Microbulbifer. Thus strain DD-13(T) represents a novel species of the genus Microbulbifer, for which the name Microbulbifer mangrovi sp. nov. is proposed with the type strain DD-13(T) ( = KCTC 23483(T) = JCM 17729(T)).