Polaromonas vacuolata gen. nov., sp. nov., a psychrophilic, marine, gas vacuolate bacterium from Antarctica.

Several strains of a novel heterotrophic gas vacuolate bacterium were isolated from antarctic marine waters. The results of phylogenetic analyses in which 16S ribosomal DAN sequencing was used, coupled with phenotypic tests, indicated that strain 34-P(T) (T = type strain) belongs to a new genus and species of the beta subgroup of the Proteobacteria, for which the name Polaromonas vacuolata is proposed. Although the other four strains studied probably belong to this new species, DNA-DNA hybridization tests were not conducted. The closest phylogenetic relatives of P. vacuolata are the photosynthetic nonsulfur purple bacterium Rhodoferax fermentans and the hydrogen autotroph Variovorax paradoxus.

Hydrogen Gas Production by an Ectothiorhodospira vacuolata Strain.

A hydrogen gas (H(2))-producing strain of Ectothiorhodospira vacuolata isolated from Soap Lake, Washington, possessed nitrogenase activity. Increasing evolution of H(2) with decreasing ammonium chloride concentrations provided evidence that nitrogenase was the catalyst in gas production. Cells were grown in a mineral medium plus 0.2% acetate with sodium sulfide as an electron donor. Factors increasing H(2) production included addition of reduced carbon compounds such as propionate and succinate, increased reducing power by increasing sodium sulfide concentrations, and increased energy charge (ATP) by increasing light intensity.

Gas vacuolate bacteria from the sea ice of antarctica.

Gas-vacuolate heterotrophic bacteria from marine habitats are reported here for the first time. They have been isolated from Antarctic sea ice microbial communities and the underlying water column. The predominant gas-vacuolate bacterium from the sea ice is filamentous and pigmented, whereas those of the water column are unicellular and nonpigmented. The highest concentrations of bacteria in sea ice were found in conjunction with the highest algal (chlorophyll a) concentrations.

Phototrophic purple and green bacteria in a sewage treatment plant.

In all purification stages of a biological sewage treatment plant, phototrophic bacteria were detected by the method of viable cell counts. The predominant species identified belonged to the genus Rhodopseudomonas of purple nonsulfur bacteria. The number of phototrophic bacteria was highest in wastewater containing sludge. In activated sludge, an average of 10(5) viable cells/ml was found; the number depended upon concentration of sludge rather than on seasonal changes in light conditions in the course of a year. Bacteriochlorophyll a was extracted from activated sludge. Relative to the viable counts of phototrophic bacteria, the content of bacteriochlorophyll a was 5- to 10-fold higher than that of three representative pure cultures. By incubation of activated and digester sludge under different environmental conditions, it was shown that phototrophic bacteria can complete with other bacteria only under anaerobic conditions in the light.

Bacterial sporulation and regulation of dihydrodipicolinate synthase in ribonucleic acid polymerase mutants of Bacillus subtilis.

The activity of dihydrodipicolinate synthase increased late in sporulation in Bacillus subtilis. Mutants blocked at several stages of sporulation due to having an altered ribonucleic acid polymerase failed to exhibit this increase.