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Three strains, designated VS-751T, VS-511 and VS-732, of a strictly anaerobic, moderately halophilic, Gram-negative, rod-shaped bacterium were isolated from a highly saline (15-20%) brine from an oil reservoir in central Oklahoma, USA. The optimal concentration of NaCl for growth of these three strains was 2 M (12%), and the strains also grew in the presence of an additional 1 M MgCl2. The strains were mesophilic and grew at a pH range of 6-8. Carbohydrates used by all three strains included glucose, fructose, arabinose, galactose, maltose, mannose, cellobiose, sucrose and inulin. Glucose fermentation products included ethanol, acetate, H2 and CO2, with formate produced by two of the three strains. Differences were noted among strains in the optimal temperature and pH for growth, the maximum and minimum NaCl concentration that supported growth, substrate utilization and cellular fatty acid composition. Despite the phenotypic differences among the three strains, analysis of the 16S rRNA gene sequences and DNA-DNA hybridizations showed that these three strains were members of the same genospecies which belonged to the genus Haloanaerobium. The phenotypic and genotypic characteristics of strains VS-751T, VS-511 and VS-732 are different from those of previously described species of Haloanaerobium. It is proposed that strain VS-751T (ATCC 700103T) be established as the type strain of a new species, Haloanaerobium kushneri.

A new cellulolytic anaerobic clostridium was isolated from the intestinal tract of pigs. The single isolate was a gram-positive, motile rod, formed terminal to subterminal swollen sporangia, and required a fermentable carbohydrate for growth. Cellulose, cellobiose, maltose, starch, and glycogen supported growth, but glucose and fructose did not. The major end products from the fermentation of cellobiose were butyrate and formate; minor amounts of hydrogen and ethanol were also formed. Ruminal fluid (15%) or yeast extract (1%) was required for good growth. The optimum temperature for growth was 39 to 42 degrees C, and the optimum pH was 6.8 to 7.2. Cell lysis occurred rapidly once stationary growth was reached. A 16S rRNA sequence analysis showed that the strain was related to a group of gram-positive anaerobes that includes Clostridium oroticum and the cellulolytic species Clostridium polysaccharolyticum and Clostridium populeti. The DNA base composition of the isolate is 38 mol% G + C. We propose the name Clostridium herbivorans for this organism; strain 54408 (= ATCC 49925) is the type strain.

A strictly anaerobic, moderately halophilic, gram-negative bacterium was isolated from a highly saline oil field brine. The bacterium was a non-spore-forming, nonmotile rod, appearing singly, in pairs, or occasionally as long chains, and measured 0.3 to 0.4 by 2.6 to 4 microns. The bacterium had a specific requirement for NaCl and grew at NaCl concentrations of between 6 and 24%, with optimal growth at 9% NaCl. The isolate grew at temperatures of between 22 and 51 degrees C and pH values of between 5.6 and 8.0. The doubling time in a complex medium containing 10% NaCl was 9 h. Growth was inhibited by chloramphenicol, tetracycline, and penicillin but not by cycloheximide or azide. Fermentable substrates were predominantly carbohydrates. The end products of glucose fermentation were acetate, ethanol, CO2, and H2. The major components of the cellular fatty acids were C14:0, C16:0, C16:1, and C17:0 cyc acids. The DNA base composition of the isolate was 34 mol% G+C. Oligonucleotide catalog and sequence analyses of the 16S rRNA showed that strain VS-752T was most closely related to Haloanaerobium praevalens GSLT (ATCC 33744), the sole member of the genus Haloanaerobium. We propose that strain VS-752 (ATCC 51327) be established as the type strain of a new species, Haloanaerobium salsugo, in the genus Haloanaerobium.

Arhodomonas aquaeolei gen. nov., sp. nov., isolated from a petroleum reservoir production fluid, is described. The single isolate was an obligately halophilic, aerobic, gram-negative, oval rod-shaped bacterium that was actively motile by means of a single polar flagellum. It was catalase and oxidase positive. The isolate had a specific requirement for NaCl; growth occurred at NaCl concentrations between 6 and 20%, and optimal growth occurred in the presence of 15% NaCl. This species metabolized primarily organic acids and required biotin for growth. The name Arhodomonas is proposed for the new genus, which was placed in the gamma subclass of the Proteobacteria on the basis of the results of a 16S rRNA sequence analysis. Although A. aquaeolei is most closely related to purple sulfur bacteria (the genera Ectothiorhodospira and Chromatium), it is not a phototrophic microorganism, which is consistent with its isolation from a subterranean environment. The major components of its cellular fatty acids were C16:0, C18:1, C19:0, C16:1, and C18:0 acids. The DNA base composition of the type strain is 67 mol% G+C. The type and only strain is strain HA-1 (= ATCC 49307).

Clostridium ljungdahlii sp. nov. strain ATCC 49587T (T = type strain) was isolated from chicken yard waste for its ability to produce ethanol from synthesis gas. This gram-positive, motile, sporeforming rod's metabolism was primarily acetogenic. C. ljungdahlii grew with carbon monoxide, hydrogen and carbon dioxide, ethanol, pyruvate, arabinose, xylose, fructose, or glucose. Methanol, ferulic acid, lactate, galactose, and mannose did not support growth. The G+C content was 22 to 23 mol%. C. ljungdahlii is the first acetogen in clostridial 23S rRNA homology group I.