School of Life Science and Technology, Wuhan Polytechnic University, Wuhan, 430023, PR China.
Hubei Accurate Inspection & Testing Co., Ltd., Wuhan, 430223, PR China.
Environ Res. 2023 Mar 1;220:115258. doi: 10.1016/j.envres.2023.115258. Epub 2023 Jan 10.
The compound 3,5-xylenol is an essential precursor used in pesticides and industrial intermediate in the disinfectants and preservatives industry. Its widespread application makes it an important source of pollution. Microbial bioremediation is more environmentally friendly than the physicochemical treatment process for removing alkylphenols from a polluted environment. However, the 3,5-xylenol-degrading bacteria is unavailable, and its degradation mechanism remains unclear. Here, a 3,5-xylenol-metabolizing bacterial strain, designated Rhodococcus sp. CHJ602, was isolated using 3,5-xylenol as the sole source of carbon and energy from a wastewater treatment factory. Results showed that strain CHJ602 maintained a high 3,5-xylenol-degrading performance under the conditions of 30.15 °C and pH 7.37. The pathway involved in 3,5-xylenol degradation by strain CHJ602 must be induced by 3,5-xylenol. Based on the identification of intermediate metabolites and enzyme activities, this bacterium could oxidize 3,5-xylenol by a novel metabolic pathway. One methyl oxidation converted 3,5-xylenol to 3-hydroxymethyl-5-methylphenol, 3-hydroxy-5-methyl benzaldehyde, and 3-hydroxy-5-methylbenzoate. After that, another methyl oxidation is converted to 5-hydroxyisophthalicate, which is metabolized by the protocatechuate pathway. It is catalyzed by a series of enzymes in strain CHJ602. In addition, toxicity bioassay result indicates that 3,5-xylenol is toxic to zebrafish and Rhodococcus sp. CHJ602 could eliminate 3,5-xylenol in water to protect zebrafish from its toxicity. The results provide insights into the bioremediation of wastewater contaminated 3,5-xylenol.
3,5-二甲苯酚是一种重要的前体化合物，用于农药和消毒剂及防腐剂工业的工业中间体。其广泛的应用使其成为重要的污染源。微生物生物修复比从污染环境中去除烷基酚的物理化学处理过程更环保。然而，缺乏 3,5-二甲苯酚降解菌，其降解机制尚不清楚。在这里，从一家污水处理厂使用 3,5-二甲苯酚作为唯一的碳源和能源，分离到一株 3,5-二甲苯酚代谢细菌，命名为 Rhodococcus sp. CHJ602。结果表明，在 30.15°C 和 pH 7.37 的条件下，菌株 CHJ602 保持了较高的 3,5-二甲苯酚降解性能。菌株 CHJ602 降解 3,5-二甲苯酚的途径必须通过 3,5-二甲苯酚诱导。基于中间代谢产物和酶活性的鉴定，该细菌可以通过一种新的代谢途径氧化 3,5-二甲苯酚。一个甲基氧化将 3,5-二甲苯酚转化为 3-羟甲基-5-甲基苯酚、3-羟基-5-甲基苯甲醛和 3-羟基-5-甲基苯甲酸。然后，另一个甲基氧化转化为 5-羟基异邻苯二甲酸，然后通过原儿茶酸途径代谢。它是由菌株 CHJ602 中的一系列酶催化的。此外，毒性生物测定结果表明，3,5-二甲苯酚对斑马鱼有毒，而 Rhodococcus sp. CHJ602 可以消除水中的 3,5-二甲苯酚，保护斑马鱼免受其毒性。该结果为受 3,5-二甲苯酚污染的废水的生物修复提供了新的见解。
