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 A degrees C (optimum 30 A degrees C) and at pH 6.0-7.5 (optimum 7.0). Phototrophic growth could not be demonstrated. No vesicular photosynthetic membrane was observed. Bacteriochlorophyll alpha 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 C-18:1 omega 6c and/or C-18:1 omega 7c (66.9 %) and C-16:0 (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.