| Summary: | Strains 18(T) 61(T) and 77 were isolated from two permanently cold fjord sediments on the west coast of Svalbard. The three psychrotolerant strains, with temperature optima at 20-23 degrees C, were able to grow at the freezing point of sea water, -2 degrees C. The strains oxidized important fermentation products such as hydrogen, formate and lactate with sulfate as the electron acceptor. Sulfate could be replaced by sulfite, thiosulfate or elemental sulfur. Poorly crystalline and soluble Fe(III) compounds were reduced in sulfate-free medium, but no growth occurred under these conditions. In the absence of electron acceptors, fermentative growth was possible. The pH optimum for the strains was around 7(.)1. The DNA G+C contents were 43(.)3 and 42(.)0 mol% for strains 18(T) and 61(T), respectively. Strains 18(T) 61(T) and 77 were most closely related to Desulfovibrio hydrothermalis (95(.)0-95(.)7% 16S rRNA gene sequence similarity), Strains 18(T) and 77, exhibiting 99(.)9% sequence similarity, represent a novel species for which the name Desulfovibrio frigidus sp. nov. is proposed. The type strain is strain 18(T) (=DSM 17176(T)=jCM 12924(T)). Strain 61(T) was closely related to strains 18(T) and 77 (97(.)6 and 97(.)5% 16S rRNA gene sequence similarity), but on the basis of DNA-DNA hybridization strain 6 1 T represents a novel species for which the name Desulfovibrio ferrireducens sp. nov. is proposed. The type strain is strain 61(T) (=DSIM 16995(=)(T)jCM 12925(T)).
|
|---|