Brachybacterium halotolerans sp. nov., a halotolerant, endophytic actinomycete isolated from branch of Bruguiera gymnoirhiza.

Abstract

A novel, aerobic, moderately halophilic Gram-positive actinomycete, strain MASK1Z-5T was isolated from a surface-sterilized branch of Bruguiera gymnoirhiza in Shankou Mangrove Nature Reserve, Guangxi, China. The taxonomic position of the strain was investigated using a polyphasic approach. Strain MASK1Z-5T tolerated up to 20% (w/v) NaCl (optimum 0-7%), and grew at pH 5.0-12.0 (optimum pH 7.0-8.0), 20-37°C (optimum 30°C). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain MASK1Z-5T belonged to the genus Brachybacterium, and showed the highest 16S rRNA gene sequence similarity of 98.0% to B. endophyticum M1HQ-2T. The cell-wall peptidoglycan contained meso-diaminopimelic acid as diagnostic diamino acid. MK-7 was the predominant menaquinone. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, one unidentified glycolipid and three unidentified lipids. The major fatty acids were anteiso-C15:0, iso-C16:0 and anteiso-C17:0. The DNA G + C content was calculated to be 71.8mol% based on the whole genome sequence. The estimated values of average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) based on whole genome sequences between strain MASK1Z-5T and B. endophyticum M1HQ-2T were 81.8% and 25.0%, respectively. The phenotypic, chemotaxonomic and genotypic properties clearly indicated that strain MASK1Z-5T represents a novel species within the genus Brachybacterium, for which the name Brachybacterium halotolerans sp. nov. is proposed. The type strain is MASK1Z-5T (= CGMCC1.18660T = JCM 34339T).