Kinetics of 1,4-dioxane biodegradation by monooxygenase-expressing bacteria
Kinetics of 1,4-dioxane biodegradation by monooxygenase-expressing bacteria
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DOI：
10.1021/es060714v
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发表时间：
2006-09-01
影响因子：
11.4
通讯作者：
Alvarez-Cohen, Lisa
中科院分区：
文献类型：
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作者：
Mahendra, Shaily;Alvarez-Cohen, Lisa
1，4-二氧六环是一种可能的人类致癌物，也是一种重要的新兴水污染物。在这项研究中，二氧六环的生物降解的20个细菌分离物进行了评估，并发现13个能够转化二氧六环。二氧六环用作食二氧杂环假诺卡氏菌CB 1190和食苯假诺卡氏菌B5的生长底物，产量分别为0.09 g蛋白g二氧六环（-1）和0.03 g蛋白g二氧六环（-1）。在用甲烷、丙烷、四氢呋喃或甲苯诱导的单加氧酶表达菌株中观察到二恶烷的共代谢转化，包括发孢甲基弯菌OB 3b、母牛分枝杆菌JOB 5、假诺卡氏菌K1、门多萨假单胞菌KR 1、皮氏罗尔斯通氏菌PKO 1、洋葱伯克霍尔德氏菌G4和红球菌RR 1。产品毒性导致许多共代谢反应的二恶烷降解不完全。短暂暴露于乙炔，一种已知的单加氧酶抑制剂，防止氧化的二氧杂环己烷在所有情况下，支持的假设，单加氧酶参与了这些菌株的二氧杂环己烷的转化。此外，大肠杆菌TG 1/pBS（Kan）含有衍生自G4、KR 1和PKO 1的甲苯-2-和甲苯-4-单加氧酶的重组质粒，也能够共代谢二氧六环转化。在50 mg/L下测得的代谢过程中的二恶烷氧化速率范围为0.01 - 0.19 mg hr（-1）mg蛋白（-1），单加氧酶诱导菌株的彗星氧化速率范围为0.1-0.38 mg hr（-1）mg蛋白（-1），重组菌株的氧化速率范围为0.17-0.60 mg hr（-1）mg蛋白（-1）。二氧六环不被M降解。表达颗粒甲烷单加氧酶的丝孢菌OB 3b、表达甲苯侧链单加氧酶的恶臭假单胞菌mt-2、以及表达甲苯-2，3-双加氧酶的恶臭假单胞菌JS 150和F1。这是第一项研究，明确显示单加氧酶在二氧杂环己烷降解中的作用，使用几个独立的证据，并描述代谢和共代谢二氧杂环己烷降解的动力学。
1,4-Dioxane is a probable human carcinogen, and an important emerging water contaminant. In this study, the biodegradation of dioxane by 20 bacterial isolates was evaluated, and 13 were found to be capable of transforming dioxane. Dioxane served as a growth substrate for Pseudonocardia dioxanivorans CB1190 and Pseudonocardia benzenivorans B5, with yields of 0.09 g protein g dioxane(-1) and 0.03 g protein g dioxane(-1), respectively. Cometabolic transformation of dioxane was observed for monooxygenase-expressing strains that were induced with methane, propane, tetrahydrofuran, or toluene including Methylosinus trichosporium OB3b, Mycobacterium vaccae JOB5, Pseudonocardia K1, Pseudomonas mendocina KR1, Ralstonia pickettii PKO1, Burkholderia cepacia G4, and Rhodococcus RR1. Product toxicity resulted in incomplete dioxane degradation for many of the cometabolic reactions. Brief exposure to acetylene, a known monooxygenase inhibitor, prevented oxidation of dioxane in all cases, supporting the hypothesis that monooxygenase enzymes participated in the transformation of dioxane by these strains. Further, Escherichia coli TG1/pBS(Kan) containing recombinant plasmids derived from the toluene-2- and toluene-4-monooxygenases of G4, KR1 and PKO1 were also capable of cometabolic dioxane transformation. Dioxane oxidation rates measured at 50 mg/L ranged from 0.01 to 0.19 mg hr(-1) mg protein(-1) for the metabolic processes, 0.1-0.38 mg hr(-1) mg protein(-1) for cometabolism by the monooxygenase-induced strains, and 0.17-0.60 mg hr(-1) mg protein(-1) for the recombinant strains. Dioxane was not degraded by M. trichosporium OB3b expressing particulate methane monooxygenase, Pseudomonas putida mt-2 expressing a toluene side-chain monooxygenase, and Pseudomonas JS150 and Pseudomonas putida F1 expressing toluene-2,3-dioxygenases. This is the first study to definitively show the role of monooxygenases in dioxane degradation using several independent lines of evidence and to describe the kinetics of metabolic and cometabolic dioxane degradation.