Sinorhodobacter ferrireducens gen. nov., sp. nov., a non-phototrophic iron-reducing bacterium closely related to phototrophic Rhodobacter species.

An Fe(III) oxide-reducing bacterium designated as SgZ-3(T), which could couple glucose oxidation to Fe(III) oxide reduction for energy conservation, was isolated from an electrochemical biofilm. The isolate was Gram-negative, catalase-positive and oxidase-negative, and facultative anaerobic. NaCl was not required for growth, but NaCl concentrations up to 5 % (w/v) were tolerated. Growth occurred in TSB (tryptic soy broth) at 20-40 °C (optimum 30 °C) and at pH 6.0-7.5 (optimum 7.0). Phototrophic growth could not be demonstrated. No vesicular photosynthetic membrane was observed. Bacteriochlorophyll α and carotenoids were absent. Biotin and thiamine were required as growth factors for the isolate. Phylogenetic analysis of the 16S rRNA gene sequence placed strain SgZ-3(T) within the family Rhodobacteraceae and affiliated with an phototrophic genera Rhodobacter. The G+C content of the genomic DNA was 68.6 mol%. Strain SgZ-3(T) contained Q-10 as the predominant quinone. The major cellular fatty acids were C18:1 ω6c and/or C18:1 ω7c (66.9 %) and C16:0 (9.5 %). Based on its phenotypic and phylogenetic properties, chemotaxonomic analysis and the results of physiological and biochemical tests, strain SgZ-3(T) (=KACC 16603(T) = CCTCC AB2012026(T)) was designated as the type strain of a new genus and a novel species of the family Rhodobacteraceae, for which the name Sinorhodobacter ferrireducens sp. nov. was proposed.