Corynebacterium humireducens sp. nov., an alkaliphilic, humic acid-reducing bacterium isolated from a microbial fuel cell

Abstract

A novel halotolerant, alkaliphilic, humic acid-reducing bacterium, designated MFC-5T, was isolated from a microbial fuel cell that was fed continuously with artificial wastewater (pH 10.0). Cells were Gram-positive-staining, facultatively anaerobic, non-fermentative, non-motile rods and had a G+C content of 59.0 mol%. Microbial growth was observed with <13 % (w/v) NaCl (optimum 10 %), at pH 7.0–11.0 (optimum pH 9.0) and at 25–45 °C (optimum 37 °C). Strain MFC-5T was active in the anaerobic reduction of a humic acid analogue, anthraquinone-2,6-disulphonate, with lactate, formate, acetate, ethanol or sucrose as the electron donor. The major cellular fatty acids were C18 : 1ω9c (42.68 %), C16 : 0 (33.69 %), C18 : 0 (7.56 %), C17 : 1ω8c (5.14 %) and C17 : 0 (3.39 %). Phylogenetic analysis demonstrated that strain MFC-5T displayed >3 % 16S rRNA gene sequence divergence from its closest relatives. Based on phenotypic, genetic and phylogenetic analysis, a novel species, Corynebacterium humireducens sp. nov., is proposed. The type strain is MFC-5T ( = NBRC 106098T  = CGMCC 2452T  = DSM 45392T).