Dataset Information

Complete Genome Sequence of Azoarcus sp. Strain DD4, a Gram-Negative Propanotroph That Degrades 1,4-Dioxane and 1,1-Dichloroethylene.

ABSTRACT: Azoarcus sp. strain DD4 can cometabolically degrade 1,4-dioxane and 1,1-dichloroethylene (1,1-DCE) when grown with propane and other substrates. The complete genome sequence of strain DD4 reveals a diverse collection of bacterial monooxygenase genes that may contribute to its versatility in degrading commingled groundwater pollutants.

SUBMITTER: Deng D

PROVIDER: S-EPMC6696649 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature

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Publications

Complete Genome Sequence of <i>Azoarcus</i> sp. Strain DD4, a Gram-Negative Propanotroph That Degrades 1,4-Dioxane and 1,1-Dichloroethylene.

Deng Daiyong D Li Fei F Ye Lei L Li Mengyan M

Microbiology resource announcements 20190815 33

<i>Azoarcus</i> sp. strain DD4 can cometabolically degrade 1,4-dioxane and 1,1-dichloroethylene (1,1-DCE) when grown with propane and other substrates. The complete genome sequence of strain DD4 reveals a diverse collection of bacterial monooxygenase genes that may contribute to its versatility in degrading commingled groundwater pollutants. ...[more]

PMID: 31416874

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Project description:Cometabolic degradation plays a prominent role in bioremediation of commingled groundwater contamination (e.g., chlorinated solvents and the solvent stabilizer 1,4-dioxane [dioxane]). In this study, we untangled the diversity and catalytic functions of multicomponent monooxygenases in Azoarcus sp. strain DD4, a Gram-negative propanotroph that is effective in degrading dioxane and 1,1-dichloroethylene (1,1-DCE). Using a combination of knockout mutagenesis and heterologous expression, a toluene monooxygenase (MO) encoded by the tmoABCDEF gene cluster was unequivocally proved to be the key enzyme responsible for the cometabolism of both dioxane and 1,1-DCE. Interestingly, in addition to utilizing toluene as a primary substrate, this toluene MO can also oxidize propane into 1-propanol. Expression of this toluene MO in DD4 appears inducible by both substrates (toluene and propane) and their primary hydroxylation products (m-cresol, p-cresol, and 1-propanol). These findings coherently explain why DD4 can grow on propane and express toluene MO for active cooxidation of dioxane and 1,1-DCE. Furthermore, upregulation of tmo transcription by 1-propanol underlines the implication potential of using 1-propanol as an alternative auxiliary substrate for DD4 bioaugmentation. The discovery of this toluene MO in DD4 and its degradation and induction versatility can lead to broad applications, spanning from environmental remediation and water treatment to biocatalysis in green chemistry.IMPORTANCE Toluene MOs have been well recognized given their robust abilities to degrade a variety of environmental pollutants. Built upon previous research efforts, this study ascertained the untapped capability of a toluene MO in DD4 for effective cooxidation of dioxane and 1,1-DCE, two of the most prevailing yet challenging groundwater contaminants. This report also aligns the induction of a toluene MO with nontoxic and commercially accessible chemicals (e.g., propane and 1-propanol), extending its implications in the field of environmental microbiology and beyond.

Project description:Biodegradation of 1,4-dioxane (dioxane) contamination has gained much attention for decades. In our previous work, we isolated a highly efficient dioxane degrader, Xanthobacter sp. YN2, but the underlying mechanisms of its extraordinary degradation performance remained unresolved. In this study, we performed a comparative transcriptome analysis of YN2 grown on dioxane and citrate to elucidate its genetic degradation mechanism and investigated the transcriptomes of different dioxane degradation stages (T0, T24, T48). We also analyzed the transcriptional response of YN2 over time during which the carbon source switched from citrate to dioxane. The results indicate that strain YN2 was a methylotroph, which provides YN2 a major advantage as a pollutant degrader. A large number of genes involved in dioxane metabolism were constitutively expressed prior to dioxane exposure. Multiple genes related to the catabolism of each intermediate were upregulated by treatment in response to dioxane. Glyoxylate metabolism was essential during dioxane degradation by YN2, and the key intermediate glyoxylate was metabolized through three routes: glyoxylate carboligase pathway, malate synthase pathway, and anaplerotic ethylmalonyl-CoA pathway. Genes related to quorum sensing and transporters were significantly upregulated during the early stages of degradation (T0, T24) prior to dioxane depletion, while the expression of genes encoding two-component systems was significantly increased at late degradation stages (T48) when total organic carbon in the culture was exhausted. This study is the first to report the participation of genes encoding glyoxalase, as well as methylotrophic genes xoxF and mox, in dioxane metabolism. The present study reveals multiple genetic and transcriptional strategies used by YN2 to rapidly increase biomass during growth on dioxane, achieve high degradation efficiency and tolerance, and adapt to dioxane exposure quickly, which provides useful information regarding the molecular basis for efficient dioxane biodegradation.

Dataset Information

Complete Genome Sequence of Azoarcus sp. Strain DD4, a Gram-Negative Propanotroph That Degrades 1,4-Dioxane and 1,1-Dichloroethylene.

Publications

Complete Genome Sequence of <i>Azoarcus</i> sp. Strain DD4, a Gram-Negative Propanotroph That Degrades 1,4-Dioxane and 1,1-Dichloroethylene.

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