Toxicity of diphenylamine and some of its nitrated and aminated derivatives to the luminescent bacterium Vibrio fischeri.

Aqueous samples containing various nitrated and aminated diphenylamine derivatives were subjected to the luminescent bacterium Vibrio fischeri NRRL-B-11177 to determine their ecotoxicological potential. As the most important toxicological parameter, EC50, the concentration needed to reduce bacterial luminescence by 50%, was calculated. All compounds tested must be classified to the category "very toxic to aquatic organisms" using the widely accepted classification scheme of D. Strupp, H.P. Lühr, H. T. Grunder, J. Gerdesmann, and J. Ahlers (1990, UWSF--Z. Umweltchem. Okotox. 2, 151-156). Only 2, 4-diaminodiphenylamine can be classified as "less toxic to aquatic organisms". EC50 values after 30, 60, and 90 min of incubation of the test compounds are presented. For many of the compounds tested in this study there are no toxicological data in the literature.

Mineralization of monofluorobenzoate by a diculture under sulfate-reducing conditions.

A mesophilic, dehalogenating, sulfate-reducing diculture was isolated from an anaerobic lake sediment. One strain of the diculture is proposed to be an endospore-forming Desulfotomaculum species, the second strain was a vibrioid, motile and non-sporeforming species which is tentatively assigned to the genus Desulfovibrio. The diculture was able to mineralize 4- and 2-fluorobenzoate both isomers being incompletely oxidized with the release of acetate, which was subsequently used by both sulfate-reducing strains. Other electron donors used for growth included benzoate, 3- and 4-hydroxybenzoate, protocatechuate, catechol, phenol, 2,5-dimethoxyphenol, fatty acids up to C8, malate and pyruvate. The culture obtained from a freshwater habitat grew optimally at NaCl concentrations of 0.3-0.5 g l-1, 33-37 degrees C, and pH 7.4. Our experiments showed that certain fluorinated aromatic hydrocarbons could serve as sole sources of carbon and energy for sulfate-reducing bacteria.

Isolation and characterization of a new spore-forming sulfate-reducing bacterium growing by complete oxidation of catechol.

A new mesophilic sulfate-reducing bacterium, strain Groll, was isolated from a benzoate enrichment culture inoculated with black mud from a freshwater ditch. The isolate was a spore-forming, rod-shaped, motile, gram-positive bacterium. This isolate was able of complete oxidation of several aromatic compounds including phenol, catechol, benzoate, p- and m-cresol, benzyl alcohol and vanillate. With hydrogen and carbon dioxide, formate or O-methylated aromatic compounds, autotrophic growth during sulfate reduction or homoacetogenesis was demonstrated. Lactate was not used as a substrate. SO4(2-), SO3(2-), and S2O3(2-) were utilized as electron acceptors. Although strain Groll originated from a freshwater habitat, salt concentrations of up to 30 g.l-1 were tolerated. The optimum temperature for growth was 35-37 degrees C. The G + C content of DNA was 42.1 mol%. This isolate is described as a new species of the genus Desulfotomaculum.