Trichloroethylene (TCE), a common groundwater contaminant, is a suspected carcinogen that is highly resistant to aerobic biodegradation. An aerobic, methane-oxidizing bacterium was isolated that degrades TCE in pure culture at concentrations commonly observed in contaminated groundwater. Strain 46-1, a type I methanotrophic bacterium, degraded TCE if grown on methane or methanol, producing CO2 and watersoluble products. Gas chromatography and 14C radiotracer techniques were used to determine the rate, methane dependence, and mechanism of TCE biodegradation. TCE biodegradation by strain 46-1 appears to be a cometabolic process that occurs when the organism is actively metabolizing a suitable growth substrate such as methane or methanol. It is proposed that TCE biodegradation by methanotrophs occurs by formation of TCE epoxide, which breaks down spontaneously in water to form dichloroacetic and glyoxylic acids and one-carbon products.

TNT was mutagenic for Salmonella typhimurium without the need of a rat liver metabolic activation system (S9). The mutagenic potency of TNT decreased in proportion to the number of nitro groups that were reduced to the amino form. The presence of a nitro group on the 4 position of the diamino congener is necessary for mutagenicity. Among the active congeners, mutagenicity was generally greater for TA100 than TA98, except that for the 4-amino congener the reverse was true. In cases when S9 was included in the assay, there was always a decrease in the number of mutants induced as compared with those without S9. Tetryl behaved like TNT, except that it was approximately three times more potent. RDX and HMX were not mutagenic under the conditions of the assay. When TNT was composed, the major metabolites identified in organic extracts of compost samples were the 2-amino and 4-amino congeners. An acetonitrile extract of compost was tested and found to be more mutagenic for TA98 than TA100, much like the authentic 4-amino congener, but the amount of this congener in the extract did not account for the degree of mutagenicity.

Ten new Legionella species were characterized on the basis of biochemical reactions, antigens, cellular fatty acids, isoprenoid quinones, and deoxyribonucleic acid relatedness. Nine of the new species were isolated from the environment, and one, Legionella hackeliae, was isolated from a bronchial biopsy specimen obtained from a patient with pneumonia. The species all exhibited the following biochemical reactions typical of the legionellae: growth on buffered cysteine-yeast extract agar, but not on blood agar; growth requirement for cysteine; gram negative; nitrate negative; urease negative; nonfermentative; catalase positive; production of a brown pigment on tyrosine-containing yeast extract agar; liquefaction of gelatin; and motility. Legionella s4iritensis was weakly positive for hydrolysis of hippurate; the other species were hippurate negative. Legionella cherrii, Legionella steigerwaltii, and Legionella parisiensis exhibited bluish white autofluorescence. Legionella rubrilucens and Legionella erythra exhibited red aqtofluorescence. The other species, L. spiritensis, L . hacke liae, Legionella maceachernii, Legionella jamestowniensis, and Legionella santicrucis did not auto fluoresce bluish white or red. All species had cellular fatty acid contents qualitatively similar to those of previously described legionellae and had major amounts of ubiquinones with more than 10 isoprene units in the side chains. Each new species was serologically distinct from previously described Legionella species. As determined by the hydroxyapatite method at 60°C, two strains of L. maceachernii were 100% related, and four strains of L. cherrii were 94 to 99% related. The other new species were represented by single strains. The levels of relatedness of the new species to each other and to previously described legionellae ranged from 1 to 67%. L . maceachernii, L. japestowniensis, and L. hackeliae were less than 25% related to other species. L. rubrilucens and L. erythra, and two red-autofluorescing species, were about 60% interrelated. L. spiritensis (a non-autofluorescing species) was 34% related to L. rubrilucens. L . santicrucis was 64% related to Legionella sainthelensi. The three bluish white-autofluorescing species, L. parisiensis, L. cherrii, and L. steigerwaltii, were most closely related to other bluish white-autofluorescing species, especially Legionella bozemanii, Legionella dumofli, Legionella gormanii, and "Legionella anisa" (35 to 67%).