A novel Sphingobacterium sp. RB, a rhizosphere isolate degrading para-nitrophenol with substrate specificity towards nitrotoluenes and nitroanilines.

Sphingobacterium sp. RB, a novel bacterial strain isolated from a soil sample, was able to utilize para-nitrophenol (PNP) as sole source of carbon and energy at high concentrations (1.0-5.

Characterization of a novel ferredoxin with N-terminal extension from Clostridium acetobutylicum ATCC 824.

A gene (CAC2657) encoding a ferredoxin (EFR1) from the strictly anaerobic soil bacterium Clostridium acetobutylicum was cloned and expressed in Escherichia coli. The ferredoxin gene encodes a polypeptide of 27 kDa that incorporates 2[4Fe-4S] clusters. An extended N-terminal region of 187 amino acid (aa) residues precedes ferredoxin domain.

Studies on inhibition of transformation of 2,4,6-trinitrotoluene catalyzed by Fe-only hydrogenase from Clostridium acetobutylicum.

The major enzyme in Clostridium acetobutylicum ATCC 824 leading to transformation of TNT has been reported to be the Fe-only hydrogenase. In this study, we examine the effect of inhibitors of hydrogenase on TNT reduction by Clostridial extracts. These experiments further demonstrate the major role of hydrogenase in TNT transformation.

Biochemical characterization of trinitrotoluene transforming oxygen-insensitive nitroreductases from Clostridium acetobutylicum ATCC 824.

The genes that encode oxygen-insensitive nitroreductases from Clostridium acetobutylicum possessing 2,4,6-Trinitrotoluene (TNT) transformation activity were cloned, sequenced and characterized. The gene products NitA (MW 31 kDa) and NitB (MW 23 kDa) were purified to homogeneity. The NitA and NitB are oxygen-insensitive nitroreductases comprised of a single nitroreductase domain.

Mutagenicity of nitroaromatic degradation compounds.

The mutagenicity of 2,4-dinitrotoluene (24DNT), and 2,6-dinitrotoluene (26DNT), and their related transformation products such as hydroxylamine and amine derivatives, which are formed by Clostridium acetobutylicum, were tested in crude cell extracts using Salmonella typhimurium TA100. A previous publication already reported the mutagenic activities of 2,4,6-trinitrotoluene (TNT) and its related hydroxylamine derivatives in this test system. A time course of the mutagenicity during the anaerobic transformation of TNT, 24DNT, and 26DNT was also investigated under the same conditions to compare with the results from the pure compounds.

2,4,6-trinitrotoluene reduction by an Fe-only hydrogenase in Clostridium acetobutylicum.

The role of hydrogenase on the reduction of 2,4,6-trinitrotoluene (TNT) in Clostridium acetobutylicum was evaluated. An Fe-only hydrogenase was isolated and identified by using TNT reduction activity as the selection basis. The formation of hydroxylamino intermediates by the purified enzyme corresponded to expected products for this reaction, and saturation kinetics were determined with a K(m) of 152 micro M.