Abstract
An iron-oxidizing bacterium, designated strain An22(T), which was isolated from a paddy field soil in Anjo, Japan, was described taxonomically. Strain An22(T) was motile by a single polar flagellum, curved-rod, Gram-negative bacterium that was able to grow at 12-37 degrees C (optimally at 25-30 degrees C) and at pH 5.2-6.8 (pH 5.9-6.1). The strain grew microaerobically and autotrophically by oxidizing ferrous iron, but did not form stalks, a umgue structure of iron oxides. The major cellular fatty acids were C-16:0 and C-16:1 omega(7c)/C-16:1 omega 6c. The major respiratory guinones were UQ-10 and UQ-8. The strain possessed ribulose-1,5-bisphosphate carboxylase/oxygenase indicating an autotrophic nature via the Calvin-Benson-Bassham cycle. The total DNA G+C content was 61.4mol%. 16S rRNA gene seguence analysis revealed that strain An22(T) was affiliated with the class Betaproteobacteria and clustered with iron-oxidizing bacteria, Galhonella ferruginea Johan (94.8% similarity) and Ferriphaselus ammcola OYT1(t) (94.4%) in the family Galhonellaceae. Based on the low 16S rRNA gene seguence similarity to the phylogenetically closest genera and the combination of umgue morphological, physiological and biochemical characteristics, strain An22(T) represents a novel genus and species within the family Galhonellaceae, for which the name Ferrigemum kumadai gen. nov., sp. nov. is proposed. The type strain is An22(T) (=JCM 30584(T)=NBRC 112974(T)=ATCC TSD-51(T)).