Pseudomonas sp. strain SCT is capable of using iodate (IO 3 − ) as a terminal electron acceptor for anaerobic respiration. A possible key enzyme, periplasmic iodate reductase (Idr), was visualized by active staining on non-denaturing gel electrophoresis. Liquid chromatography-tandem mass spectrometry analysis revealed that at least four proteins, designated as IdrA, IdrB, IdrP 1 , and IdrP 2 , were involved in Idr. IdrA and IdrB were homologues of catalytic and electron transfer subunits of respiratory arsenite oxidase (Aio); however, IdrA defined a novel clade within the dimethylsulfoxide (DMSO) reductase family. IdrP 1 and IdrP 2 were closely related to each other and distantly related to cytochrome c peroxidase. The idr genes (idrABP 1 P 2 ) formed an operon-like structure, and their transcription was upregulated under iodate-respiring conditions. Comparative proteomic analysis also revealed that Idr proteins and high affinity terminal oxidases (Cbb 3 and Cyd), various H 2 O 2 scavengers, and chlorite (ClO 2 − ) dismutase-like proteins were expressed specifically or abundantly under iodate-respiring conditions. These results suggest that Idr is a respiratory iodate reductase, and that both O 2 and H 2 O 2 are formed as by-products of iodate respiration. We propose an electron transport chain model of strain SCT, in which iodate, H 2 O 2 , and O 2 are used as terminal electron acceptors.

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Bacillus selenatarsenatis sp. nov., a selenate-and arsenate-reducing bacterium isolated from the effluent drain of a glass-manufacturing plant was isolated from a selenium-contaminated sediment obtained from an effluent drain of a glass-manufacturing plant in Japan. The bacterium stained Gram-positive and was a motile, spore-forming rod capable of respiring with selenate, arsenate and nitrate as terminal electron acceptors. The major cellular fatty acids of the strain were iso-C 15 : 0 , iso-C 17 : 1 v10c and C 16 : 1 v7c alcohol. The G+C content of the genomic DNA was 42.8 mol%. Though the nearest phylogenetic neighbour was Bacillus jeotgali JCM 10885 T , with a 16S rRNA gene sequence similarity of 99.6 %, DNA-DNA hybridization studies showed only 14 % relatedness between these strains, a level that is clearly below the value recommended to delimit different species. This, together with the phenotypic differences (utilization of electron acceptors, NaCl tolerance), suggests that strain SF-1 T represents a novel species of the genus Bacillus, for which the name Bacillus selenatarsenatis sp. nov. is proposed. The type strain is SF-1 T (=JCM 14380 T =DSM 18680 T ).

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