Discovery of an inducible toluene monooxygenase that cooxidizes 1,4-dioxane and 1,1-dichloroethylene in propanotrophic azoarcus sp. strain DD4
Document Type
Article
Publication Date
9-1-2020
Abstract
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.
Identifier
85089786846 (Scopus)
Publication Title
Applied and Environmental Microbiology
External Full Text Location
https://doi.org/10.1128/AEM.01163-20
e-ISSN
10985336
ISSN
00992240
PubMed ID
32591384
Issue
17
Volume
86
Grant
1846945
Fund Ref
National Science Foundation
Recommended Citation
Deng, Daiyong; Pham, Dung Ngoc; Li, Fei; and Li, Mengyan, "Discovery of an inducible toluene monooxygenase that cooxidizes 1,4-dioxane and 1,1-dichloroethylene in propanotrophic azoarcus sp. strain DD4" (2020). Faculty Publications. 5022.
https://digitalcommons.njit.edu/fac_pubs/5022
