Desulforegula conservatrix gen. nov., sp nov., a long-chain fatty acid-oxidizing, sulfate-reducing bacterium isolated from sediments of a freshwater lake

A novel sulfate-reducing bacterium, strain Mb1Pa(T), was isolated from the sediments of a freshwater floodplain lake. Cells of strain Mb1Pa(T) were rod-shaped, 1-1.3 mum wide and 2.6-3 mum long, motile and Gram-negative. The bacterium grew on straight-chain carboxylic acids with 4-17 carbon atoms. Electron donors with an even number of carbon atoms were oxidized to acetate and electron donors with an odd number of carbon atoms were oxidized to acetate and propionate. No other compounds were found to be used as electron donors. No growth occurred in the absence of sulfate. The optimum temperature for growth was between 25 and 30 degreesC and the maximum temperature for growth was 32 degreesC. Strain Mb1Pa(T) grew very slowly in medium with 5 g NaCl l(-1) with optimum growth occurring with up to 1.0 g NaCl l(-1). Analysis of the 16S rRNA gene showed that strain Mb1Pa(T) belonged to the delta -subclass of the Proteobacteria, was a member of the family Desulfobacteraceae, but lacked similarity with any currently described representatives. The combined phylogenetic analysis and physiological data indicate that strain Mb1Pa(T) represents a new genus and the name Desulforegula conservatrix is proposed. The type strain is Mb1Pa(T) (= DSM 13527(T) = ATCC BAA-134(T)).