一株1,4-二噁烷降解菌的分离及其降解性能解析

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

摘要:

为应对水环境中潜在致癌物质1,4-二噁烷(1,4-dioxane)的污染，本研究从1,4-二噁烷污染的地下水中，通过富集驯化、分离得到一株1,4-二噁烷高效降解菌株DXTK-010。经过形态学观察、16S rRNA基因序列比对以及基于全基因组的物种分类研究，鉴定该菌株为觧胺胺杆菌(Aminobacter aminovorans)。研究结果表明，该菌株具有较强的环境适应能力，在20−37℃及pH 5.0−8.0下均能有效降解1,4-二噁烷。单因素实验表明，在30℃、pH 7.5条件下降解性能最佳。在优选条件下，该菌株能在24 h内完全降解200 mg/L的1,4-二噁烷，最大降解速率达9.367 mg/(L·h)。菌株DXTK-010对1,4-二噁烷的降解动力学采用Monod方程进行拟合，其最大比降解速率(V_max)为0.224 mg 1,4-dioxane/(mg protein·h)，半饱和浓度(K_s)为41.350 mg/L，细胞产率(Y)为0.130 mg protein/(mg 1,4-dioxane)，与已报道的降解菌相比，DXTK-010作为优异的降解菌株，扩充了生物修复1,4-二噁烷的菌株资源。全基因组测序揭示其完整基因组包括1条环状染色体和3个质粒。功能基因分析表明，丙烷单加氧酶基因簇和醇脱氢酶基因是其高效降解1,4-二噁烷的关键功能基因。本研究为DXTK-010实际应用于1,4-二噁烷污染修复提供了理论基础。

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.