Desulfovibrio mexicanus sp nov., a sulfate-reducing bacterium isolated from an upflow anaerobic sludge blanket (UASB) reactor treating cheese wastewaters

A mesophilic sulfate-reducing bacterium, designated strain Lup1(T) (T=type strain) was isolated from a Mexican UASB digester treating cheese factory w astewater. The non-motile, Gram-negative, curved and non-spore-forming cell s (1.7-2.5 x 0.5 mu m) existed singly or in chains. Optimum growth occurred at 37 degrees C and pH 7.2 in a medium containing lactate and thiosulfate. Strain Lup1(T) used pyruvate, formate, Casamino acids, serine, cysteine, H -2 and ethanol as electron donors in the presence of thiosulfate as an elec tron acceptor and fermented pyruvate, Casamino acids, cysteine, and serine. Sulfate, elemental sulfur, and sulfite also served as electron accepters b ut not nitrate or fumarate. Thiosulfate was disproportionated to sulfate an d sulfide. The G+C content of the DNA was 66 mol%. Phylogenetic analysis ba sed on 16S rDNA revealed that strain Strain Lup1(T) was a member of the gen us Desulfovibrio with Desulfovibrio aminophilus being the closest relative (similarity value of 91%). As strain Lup1(T) is physiologically and phyloge netically different from other Desulfovibrio species, it is designated Desu lfovibrio mexicanus sp. nov (=DSM 13116). (C) 2000 Academic Press.