Analysis of the Metabolites of Indole Degraded by an Isolated Acinetobacter pittii L1

Received Aug 27, 2017; Accepted Nov 19, 2017

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1. Introduction

Indole and its derivatives, with highly toxic and carcinogenic properties, are mainly generated in large quantities as a result of industrial wastewater from pharmaceutical synthesis, fuel, cosmetics, pesticide, disinfectant, agrochemicals, and dyestuff and have recently gained wide attention [1–4]. These compounds also existed in large amounts of livestock manure emissions, which are serious pollution to the ecological environment with a sharp odor. Their heterocyclic structure makes them not only merely more soluble but also more difficult to degradation; therefore these cyclic compounds could be transformed through the soil and contaminated ground water.

Indole is a typical tryptophan metabolite in the natural environment, acting as plant hormone precursor and microbial signal molecule [5–7]. Furthermore, indole also acted as a gas pollutant because of its unfavorable odor, especially released from the pharmaceutical, coking, and livestock wastewater.

The technologies of contact glow discharge plasma degradation, photocatalytic degradation, and electro-Fenton oxidation were used to degrade indole, and the chemical oxidants such as chlorine and chlorine dioxide were used to control indole release [8, 9]. The photocatalytic degradation and chemical oxidation can efficiently break up indole, but the high investment and energy consumption confined the engineering applications, and the chemical oxidants could induce new toxic and carcinogenic compounds [8, 10, 11].

Some bacteria demonstrated their abilities of decomposing N-heterocyclic compounds. For example, a novel endophytic fungus Phomopsis liquidambari could catalyze indole into 2-aminobenzoic acid and 2-dioxindole and an isolated strain Bacillus sp. from petroleum-contaminated soil was able to decompose quinoline under aerobic conditions [12, 13]. Bacteria from genera Alicycliphilus, Alcaligenes, and Thauera were thought to be responsible for indole degradation [4]. Moreover, Qu et al. indicated that a rich set of oxidoreductases was expressed from a newly isolated Cupriavidus sp. SHE, which might...