Desulfobulbus oligotrophicus sp. nov., a sulfate-reducing and propionate-oxidizing bacterium isolated from a municipal anaerobic sewage sludge digester.

A novel, mesophilic, strictly anaerobic, sulfate-reducing and propionate-oxidizing bacterium, strain Prop6T, was enriched and isolated from a municipal anaerobic sewage sludge digester. Cells were Gram-stain-negative, catalase-positive, oval rods, motile by means of amphitrichous flagella, non-spore-forming and contained menaquinone MK-5(H2) as the major respiratory quinone. The genomic DNA G+C content was 51.7 mol%. The optimal NaCl concentration, temperature and pH were 2-5 g l-1, 35 °C and pH 7.6, respectively. Strain Prop6T could only oxidize propionate, lactate and pyruvate (weakly) with sulfate, sulfite or thiosulfate, mainly to acetate. Strain Prop6T fermented pyruvate and lactate to acetate and propionate. The predominant cellular fatty acids were C14 : 0, C16 : 0, C16 : 1ω7, C16 : 1ω5, C17 : 1ω6 and C18 : 1ω7. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the newly isolated strain was a member of the genus Desulfobulbus, with Desulfobulbus elongatus DSM 2908T, Desulfobulbus propionicus DSM 2032T and Desulfobulbus rhabdoformis DSM 8777T as closest relatives among species with validly published names. On the basis of genotypic, phenotypic and chemotaxonomic characteristics, it is proposed that the isolate represents a novel species, Desulfobulbus oligotrophicus sp. nov. The type strain is Prop6T (=DSM 103420T=JCM 31535T).

Desulfovibrio marrakechensis sp. nov., a 1,4-tyrosol-oxidizing, sulfate-reducing bacterium isolated from olive mill wastewater.

A novel mesophilic sulfate-reducing bacterium, EMSSDQ(4)(T), was isolated from olive mill wastewater in the semi-arid region of Morocco (Marrakech). Cells were Gram-negative, catalase-positive, straight rods that were non-motile and non-spore-forming and contained cytochrome c(3) and desulfoviridin. The DNA G+C content was 65.1 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolate was a member of the genus Desulfovibrio with Desulfovibrio carbinoliphilus D41(T), Desulfovibrio alcoholivorans SPSN(T), Desulfovibrio fructosivorans JJ(T) and Desulfovibrio carbinolicus EDK82(T) as the most closely related strains with validly published names. In addition to the classical substrates used by Desulfovibrio species, the isolate oxidized 1,4-tyrosol, one of the most abundant phenolic compounds occurring in olive mill wastewater, to 4-hydroxyphenylacetate without ring cleavage. D. alcoholivorans SPSN(T) was also found to carry out this reaction. Under air, strain EMSSDQ(4)(T) exhibited limited growth on lactate and yeast extract in the absence of sulfate. On the basis of genotypic and phenotypic characteristics, it is proposed that the isolate represents a novel species, Desulfovibrio marrakechensis sp. nov. The type strain is EMSSDQ(4)(T) (=DSM 19337(T) =ATCC BAA-1562(T)).

Clostridiisalibacter paucivorans gen. nov., sp. nov., a novel moderately halophilic bacterium isolated from olive mill wastewater.

A moderately halophilic, strictly anaerobic bacterium, designated 37HS60(T), was isolated from an olive mill wastewater in southern Morocco (Marrakesh). The cells were straight, motile and stained Gram-positive, forming spherical and terminal spores and with an atypical thick and stratified multilayered cell wall. Major fatty acid components were iso-C17:1omega10c or anteiso-C17:1omega3c (19.3%), C14:0 (14.3%), C16:1omega7c (9.9%), C16:1omega7c DMA (8.5%) and C16:0 (7.6%). Strain 37HS60(T) grew from 20 to 50 degrees C with an optimum at 40-45 degrees C, and growth was observed from pH 5.5 to 8.5 with an optimum of 6.8. The salinity range for growth was 10-100 g NaCl l(-1) with an optimum at 50 g NaCl l(-1). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 37HS60(T) fell within the evolutionary radiation enclosed by cluster XII of the Clostridium subphylum. Strain 37HS60(T) exhibited highest 16S rRNA gene sequence similarity of 92.0% with Caloranaerobacter azorensis and 90.6% with Clostridium purinilyticum. Moreover, 37HS60(T) did not grow on basal medium with hexose or pentose sugars as carbon and energy sources. Pyruvate, fumarate and succinate were the best substrates for 37HS60(T) growth with 1.0 g yeast extract l(-1). The DNA G+C content was 33.0 mol%. Due to its phenotypic and genotypic characteristics, isolate 37HS60(T) is proposed as a novel species of a new genus, Clostridiisalibacter paucivorans gen. nov., sp. nov. The type strain is 37HS60(T) (=JCM 14354(T)=CCUG 53849(T)).