Isolation and degradation characterization of a 1,4-dioxane-degrading bacterial strain

Abstract:

To address the potential pollution caused by the carcinogen 1,4-dioxane in aquatic environments, we isolated a highly efficient 1,4-dioxane-degrading bacterial strain, designated as DXTK-010, from the groundwater contaminated by 1,4-dioxane. According to the morphological characteristics, the phylogenetic tree established based on the 16S rRNA gene sequence, and the whole genome sequence, we identified DXTK-010 as Aminobacter aminovorans. This strain demonstrated robust degradation capacity within a temperature range of 20 ℃ to 37 ℃ and a pH range of 5.0 to 8.0. Furthermore, single-factor experiments indicated the optimal degradation conditions at 30 ℃ and pH 7.5. Under the optimal conditions, the strain completely degraded 200 mg/L of 1,4-dioxane within 24 h, achieving a maximum degradation rate of 9.367 mg/(L·h). The Monod equation was adopted to fit the degradation kinetics of 1,4-dioxane at different initial concentrations, which revealed a maximum specific degradation rate of 0.224 mg 1,4-dioxane/(mg protein·h), a half-saturation constant (K_s) of 41.350 mg/L, and a cell yield of 0.130 mg protein/(mg 1,4-dioxane). Whole genome sequencing revealed a circular chromosome and three plasmids within DXTK-010. Functional gene annotation and analysis underscored the significance of the propane monooxygenase gene cluster and alcohol dehydrogenase gene in facilitating the efficient degradation of 1,4-dioxane by this strain. DXTK-010 outperformed the existing degraders for 1,4-dioxane, expanding the strain resources for the bioremediation of 1,4-dioxane pollution. This study provides a theoretical basis for the practical application of DXTK-010 in the remediation of 1,4-dioxane pollution.