State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China.
College of Energy and Environmental Engineering, Hebei University of Engineering, Handan 056107, China.
Int J Mol Sci. 2021 Sep 28;22(19):10435. doi: 10.3390/ijms221910435.
Biodegradation of 1,4-dioxane (dioxane) contamination has gained much attention for decades. In our previous work, we isolated a highly efficient dioxane degrader, 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 and , 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.
几十年来，1,4-二恶烷（二恶烷）污染的生物降解一直备受关注。在我们之前的工作中，我们分离出了一种高效的二恶烷降解菌， sp. YN2，但它非凡的降解性能的潜在机制仍未得到解决。在这项研究中，我们对YN2 在二恶烷和柠檬酸盐上生长进行了比较转录组分析，以阐明其遗传降解机制，并研究了不同二恶烷降解阶段（T0、T24、T48）的转录组。我们还分析了YN2 从柠檬酸盐切换到二恶烷作为碳源时随时间的转录响应。结果表明，菌株 YN2 是一种甲醇营养型微生物，这为 YN2 作为污染物降解菌提供了主要优势。大量与二恶烷代谢相关的基因在接触二恶烷之前就被组成性表达。用二恶烷处理后，与每个中间产物的分解代谢相关的多个基因被上调。乙醛酸代谢在 YN2 降解二恶烷过程中是必不可少的，关键的中间产物乙醛酸通过三条途径进行代谢：乙醛酸羧基裂合酶途径、苹果酸合酶途径和回补乙基丙二酰辅酶 A 途径。在降解早期（T0、T24），即在二恶烷耗尽之前，与群体感应和转运体相关的基因显著上调，而在晚期降解阶段（T48），当培养物中的总有机碳耗尽时，编码双组分系统的基因表达显著增加。本研究首次报道了参与二恶烷代谢的基因编码甘氨酸酶，以及甲醇营养型基因 和 。本研究揭示了 YN2 在二恶烷上生长时快速增加生物量、实现高效降解效率和耐受性以及快速适应二恶烷暴露所采用的多种遗传和转录策略，为高效二恶烷生物降解的分子基础提供了有用信息。
