Shewanella shenzhenensis sp. nov., a novel Fe(III)-reducing bacterium with abundant possible cytochrome genes, isolated from mangrove sediment.

Abstract

A facultative anaerobic bacterium, designated as A25T, was isolated from a mangrove sediment sample collected in Shenzhen, China. Cells of strain A25T were found to be Gram-staining negative, rod-shaped, flagella-harboring, and oxidase- and catalase-positive. The isolate was able to grow at 4-40°C (optimum 28°C) and pH 5.0-9.0 (optimum pH 6.0), and in 0-10% NaCl concentration (w/v) (optimum 1%). Strain A25T was capable of reducing Fe(III) citrate under anaerobic conditions. The major fatty acids of this strain was C16:1ω7c/C16:1ω6c (summed feature 3), C17:1ω8c and iso-C15:0. Results of phylogenetic analyses based on 16S rRNA gene sequences indicated that strain A25T is affiliated with the genus Shewanella, showing the highest similarity to Shewanella seohaensis S7-3T (98.4% similarity). The average nucleotide identity and digital DNA-DNA hybridization values between the genomes of strain A25T and its closely related strains were ≤ 79.0% and ≤ 22.8%, respectively. Based on its phenotypic, phylogenetic properties and physiological and biochemical characteristics, strain A25T (= JCM 34900T = GDMCC 1.2731T) was designated as the type strain of a novel species of the genus Shewanella, for which the name Shewanella shenzhenensis sp. nov. was proposed.