Aerobic biotransformation of 3-methylindole to ring cleavage products by Cupriavidus sp. strain KK10

Abstract

3-Methylindole, also referred to as skatole, is a pollutant of environmental concern due to its persistence, mobility and potential health impacts. Petroleum refining, intensive livestock production and application of biosolids to agricultural lands result in releases of 3-methylindole to the environment. Even so, little is known about the aerobic biodegradation of 3-methylindole and comprehensive biotransformation pathways have not been established. Using glycerol as feedstock, the soil bacterium Cupriavidus sp. strain KK10 biodegraded 100 mg/L of 3-methylindole in 24 h. Cometabolic 3-methylindole biodegradation was confirmed by the identification of biotransformation products through liquid chromatography electrospray ionization tandem mass spectrometry analyses. In all, 14 3-methylindole biotransformation products were identified which revealed that biotransformation occurred through different pathways that included carbocyclic aromatic ring-fission of 3-methylindole to single-ring pyrrole carboxylic acids. This work provides first comprehensive evidence for the aerobic biotransformation mechanisms of 3-methylindole by a soil bacterium and expands our understanding of the biodegradative capabilities of members of the genus Cupriavidus towards heteroaromatic pollutants.

Isolation and characterization of two Acinetobacter species able to degrade 3-methylindole

“…Aerobic biodegradation and comprehensive biotransformation mechanisms of 3MI revealed in a soil bacterium Cupriavidus sp . Strain KK10 which biodegraded 100 mg/L of 3MI in 24 hours [9]. Compared with the above species, our strains NTA1-2A and TAT1-6A exhibited rapid degradation efficiency at concentrations ranging from 65–200 mg/L within the first 6 days (Figs 7 and 8).…”

“…In the last two decades, many pollutant-degrading microbes have been isolated from the environments, including strains capable of heterotrophic ammonia removal [28] and degradation of long-chain hydrocarbons [17] and aromatic compounds such as phenol and chlorophenol [19–21]. Because 3-methylindole is hazardous to the environment and human and animal welfare, and is difficult to degrade in nature, numerous studies have isolated and evaluated bacterial strains capable of degrading 3MI from different environments [9, 13–16, 28–31]. Our paper is the first report that the genus Acinetobacter isolated from chicken manure is capable of degrading 3MI.…”

“…Additionally, the degradation potential of the two strains isolated in this study is better compared with others in 3MI removal ability except Cupriavidus sp . Strain KK10 [9].…”

“…Due to their persistence, mobility, and potential impacts on the environment and human and animal welfare, studies of indolic compounds (such as 3MI) from waste treatment plants have highlighted microorganisms capable of its biodegradation [9]. For example, several studies have investigated bacterial and fungal biodegradation of indolic compounds [9–11] under variable conditions. In a study of pig and chicken manure composting processes, Kohda et al .…”

Biotechnological Properties of Sponges from Northeast Brazil: Cliona varians as a Biocatalyst for Enantioselective Reduction of Carbonyl Compounds

“…27 However, few studies in the literature have focused on the biotransformation of isatin derivatives by whole cells. 28 The structure of the substrate is a determining factor for the stereochemical course of bioreduction reactions. 29 The choice of structures was made in order to verify the influence of the relative steric volumes of the alkoxy groups of 2-oxoglutarate, compared with isatin 1 and ethyl pyruvate (2).…”