Salimesophilobacter vulgaris gen. nov., sp. nov., an anaerobic bacterium isolated from paper-mill wastewater

Abstract

A novel anaerobic, heterotrophic bacterium, designated strain Zn2(T), was isolated from the wastewater of a paper mill in Zhejiang, China. Cells were gram-type-positive rods, 0.5-0.8 µm wide and 2-4 µm long, and were motile by a lateral flagellum. The ranges of temperature and pH for growth were 10-50 °C and pH 6.0-9.5. Optimal growth occurred at 35 °C and pH 7.3-7.5. The strain did not require NaCl for growth, but its inclusion in the medium improved growth (optimum concentration 6 %). Substrates utilized as sole carbon sources were peptone, tryptone, Casamino acids, D-xylose, salicin, glycerol, formate, acetate and propionate. The main products of carbohydrate fermentation were acetate, formate, propionate and lactate. Elemental sulfur, thiosulfate and Fe(III) were used as electron acceptors, but sulfate, sulfite, nitrate, nitrite and Mn(IV) were not. Growth was inhibited by the addition of 10 µg ampicillin, penicillin, tetracycline or chloramphenicol ml(-1). iso-C15 : 0, C14 : 0, C16 : 0, C16 : 1 cis9 and C18 : 1 cis9 were the major fatty acids. Strain Zn2(T) did not contain any detectable menaquinones or ubiquinones. The main polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylserine, two unknown phospholipids and four unknown glycolipids. The genomic DNA G+C content was 37 mol%, as determined by HPLC. 16S rRNA gene sequence analysis revealed that strain Zn2(T) was a member of family Clostridiaceae, and was most closely related to the type strains of Geosporobacter subterraneus, Thermotalea metallivorans and Caminicella sporogenes, showing 91.2, 90.3 and 91.1 % sequence similarity, respectively. On the basis of its phenotypic and genotypic properties, strain Zn2(T) is suggested to represent a novel species of a new genus, for which the name Salimesophilobacter vulgaris gen. nov., sp. nov. is proposed. The type strain of Salimesophilobacter vulgaris is Zn2(T) ( = DSM 24770(T) = JCM 17796(T)).