Metalloid Reducing Bacteria Isolated from Deep Ocean Hydrothermal Vents of the Juan de Fuca Ridge, Pseudoalteromonas telluritireducens sp. nov. and Pseudoalteromonas spiralis sp. nov

Five strains of Gram-negative, rod, curved rod and spiral-shaped bacteria were isolated from the vicinity of deep ocean hydrothermal vents along the Main Endeavour Segment of the Juan de Fuca Ridge in the Pacific Ocean. All strains showed remarkable resistance to high levels of toxic metalloid oxyanions, and were capable of reducing the oxyanions tellurite and selenite to their less toxic elemental forms. Phylogenetic analysis of four strains identified these isolates as close relatives of the genus Pseudoalteromonas within the class Gammaproteobacteria. Pseudoalteromonas agarivorans was the closest relative of strains Te-1-1 and Se-1-2-red^T, with, respectively, 99.5 and 99.8% 16S rDNA sequence similarity. Strain Te-2-2^T was most closely related to Pseudoalteromonas paragorgicola, with 99.8% 16S rDNA sequence similarity. The DNA G+C base composition was 39.6 to 41.8 mol%, in agreement with other members of the genus Pseudoalteromonas. However, the isolates showed important morphological and physiological differences from previously described species of this genus, with one group forming rod-shaped bacteria typical of Pseudoalteromonas and the other forming vibrioid- to spiral-shaped cells. Based on these differences, and on phylogenetic data, we propose the creation of the new species Pseudoalteromonas telluritireducens sp. nov., with strain Se-1-2-red^T (DSMZ=16098^T=VKM B-2382^T) as the type strain, and Pseudoalteromonas spiralis sp. nov., with strain Te-2-2^T (DSMZ=16099^T=VKM B-2383^T) as the type strain. The EMBL accession numbers for the 16S rDNA sequences are: Te-1-1, AJ314843; Te-2-2^T, AJ314842; Se-1-2-or, AJ314844; Se-1-2-red^T, AJ314845.