Cometabolic Degradation of Dibenzofuran and Dibenzothiophene by a Newly Isolated Carbazole-Degrading Sphingomonas sp. Strain

Abstract

A carbazole-utilizing bacterium was isolated by enrichment from petroleum-contaminated soil. The isolate, designated Sphingomonas sp. strain XLDN2-5, could utilize carbazole (CA) as the sole source of carbon, nitrogen, and energy. Washed cells of strain XLDN2-5 were shown to be capable of degrading dibenzofuran (DBF) and dibenzothiophene (DBT). Examination of metabolites suggested that XLDN2-5 degraded DBF to 2-hydroxy-6-(2-hydroxyphenyl)-6-oxo-2,4-hexadienic acid and subsequently to salicylic acid through the angular dioxygenation pathway. In contrast to DBF, strain XLDN2-5 could transform DBT through the ring cleavage and sulfoxidation pathways. Sphingomonas sp. strain XLDN2-5 could cometabolically degrade DBF and DBT in the growing system using CA as a substrate. After 40 h of incubation, 90% of DBT was transformed, and CA and DBF were completely removed. These results suggested that strain XLDN2-5 might be useful in the bioremediation of environments contaminated by these compounds.

Performance and microbial community composition in a long-term sequential anaerobic-aerobic bioreactor operation treating coking wastewater

“…2, although anaerobic treatment was not effective, the combined system was quite efficient for the removal of SCN − (98.2 %) and CN − (85.4 %) ( Table S1). Degradation of SCN − , CN − , and other nitrogen and sulfur heterocyclic organic compounds was responsible for the release of ammonium and sulfate (Felföldi et al 2010;Staib and Lant 2007;Vazquez et al 2006;Maranon et al 2008;Gai et al 2007). Oxidation of sulfides and thiosulfate (Shoji et al 2014) may have also contributed to the increased concentration of inorganic sulfate in the aerobic effluent.…”

Aerobic Degradation of Petroleum Components by Microbial Consortia

“…In comparison with desulfurization pathway, the enzymes for lateral dioxygenation and consecutive reactions are very different (Kodama pathway, Scheme 7). Many bacterial species have been reported to metabolize dibenzothiophene through Kodama pathway [120,150,165]. Although no detailed research has been done, the structural similarities of the metabolites suggest that common PAH dioxygenase and enzymes in successive steps may be involved in Kodama pathway.…”

“…These enzymes were found in Gram-positive and negative bacteria [138,152,[154][155][156]. Many bacterial strains have the ability to use carbazole as the sole carbon, nitrogen and energy source [150,157]. Most isolates degraded carbazole by following the so-called angular pathway, in which carbazole is initially attacked at the 1 and 9a positions by carbazole dioxygenase, followed by the spontaneous conversion of the dihydroxylated intermediate to 2'-aminobiphenyl-2,3-diol (Scheme 6).…”

“…Heteroaromatic compounds: Many bacterial species have been reported to decompose dibenzofurans and carbazole, a structural analogue with nitrogen instead of oxygen [149][150][151][152][153]. Guo et al [151] isolated a stable carbazole-degrading microbial consortium consisting of Chryseobacterium sp.…”

“…Most isolates degraded carbazole by following the so-called angular pathway, in which carbazole is initially attacked at the 1 and 9a positions by carbazole dioxygenase, followed by the spontaneous conversion of the dihydroxylated intermediate to 2'-aminobiphenyl-2,3-diol (Scheme 6). An extradiol dioxygenase then attacks the hydroxylated ring at the meta position to give 2-hydroxy-6-(2'-aminophenyl)-6-oxo-2,4-hexadienoic acid, which is hydrolysed to produce anthranilic acid and 2-hydroxypenta-2,4-dienoic acid [150,[154][155][156][157].…”