Reduction of nitroaromatic compounds by anaerobic bacteria isolated from the human gastrointestinal tract

Abstract

Human intestinal microbial flora were screened for their abilities to reduce nitroaromatic compounds by growing them on brain heart infusion agar plates containing 1-nitropyrene. Bacteria metabolizing 1-nitropyrene, detected by the appearance of clear zones around the colonies, were identified as Clostridium leptum, Clostridium paraputrificum, Clostridium clostridiiforme, another Clostridium sp., and a Eubacterium sp. These bacteria produced aromatic amines from nitroaromatic compounds, as shown by thin-layer chromatography, high-pressure liquid chromatography, and biochemical tests. Incubation of three of these bacteria with 1nitropyrene, 1,3-dinitropyrene, and 1,6-dinitropyrene inactivated the direct-acting mutagenicity associated with these compounds. Menadione and o-iodosobenzoic acid inhibited nitroreductase activity in all of the isolates, indicating the involvement of sulfhydryl groups in the active site of the enzyme. The optimum pH for nitroreductase activity was 8.0. Only the Clostridium sp. required added flavin adenine dinucleotide for nitroreductase activity. The nitroreductases were constitutive and extracellular. An activity stain for the detection of nitroreductase on anaerobic native polyacrylamide gels was developed. This activity stain revealed only one isozyme in each bacterium but showed that the nitroreductases from different bacteria had distinct electrophoretic mobilities.

Inhibition of the lignin peroxidase of Phanerochaete chrysosporium by hydroxylamino-dinitrotoluene, an early intermediate in the degradation of 2,4,6-trinitrotoluene

“…The reduction of TNT and various other nitroaromatic compounds by Pseudomonas species under aerobic (20) and anaerobic conditions by a sulfate-reducing bacterium was described previously (17). Nitroreductases have been found in members of the genera Enterobacter (6), Nocardia (35), and Neurospora (37) and anaerobic bacteria of the human gastrointestinal tract (18). Nitroreductase activity of P. chrysosporium was mentioned by Valli et al (34) for the reduction of 2,4-dinitrotoluene.…”

Change of bacterial communities in sediments along Songhua River in Northeastern China after a nitrobenzene pollution event

“…and showed a relationship with Clostridium acetobutylicum and Clostridium thermoaceticum . It has been reported that C. acetobutylicum and C. thermoaceticum could reduce the nitro group of nitroaromatics to the corresponding amines (Rafii et al , 1991; Gorontzy et al , 1993; Khan et al , 1997; Huang et al , 2000). These results suggest that Clostridium may play a role in reduction of the nitro group of nitrobenzene in polluted sediments of this study.…”

Metabolism and Disposition of a Novel B-Cell Lymphoma-2 Inhibitor Venetoclax in Humans and Characterization of Its Unusual Metabolites

“…reported to undergo gut bacteria-mediated nitro reduction, resulting in the formation of primary amine metabolites (Koch et al, 1980;Elmer and Remmel, 1984;Takeno et al, 1990). Clostridium and Eubacterium have been identified from human intestinal microbial flora as the anaerobic bacteria capable of producing nitroreductases and reducing nitro aromatic compounds (Rafil et al, 1991).…”