ENVIRONMENTAL POLLUTION
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2020
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IF 6.793
Kai Sun,Xing Cheng,Jialin Yu,Luojian Chen,Jiajun Wei,Wenjun Chen,Jun Wang,Shunyao Li,Qingzhu Liu,Youbin Si
Estrogens, which are extensive in the eco-environments, are a category of high-toxic emerging contaminants that induce metabolic disorders and even carcinogenic risks in wildlife and humans. Here we investigate whether fungus-secreted laccase can be used as a green catalyst to eliminate a representative estrogen, 17 β -estradiol (E2). A white-rot fungus Trametes hirsuta La-7 with high laccase-productivity, was isolated from pig manure-contaminated soil. Extracellular laccase activity expressed by strain La-7 was 65.4 U·mL −1 for a 3 d inoculation under the optimal fermentation parameters. The concentrated-crude laccase from Trametes hirsuta La-7 (CC- Th Lac) was capable of effectively metabolizing E2 at pH 4–6, and the apparent pseudo first-order reaction rate constant and half-life values were respectively 0.027–0.055 min −1 and 25.86–12.67 min ( R 2 > 0.98). The mass measurement of high-resolution mass spectrometry in combination with 13 C-isotope labeling identified that the main by-products of E2 metabolism were dimers, trimers , and tetramers, which are consistent with radical-driven C–C and/or C–O–C covalent coupling pathway, involving the initial enzymatic production of phenoxy radical intermediates and then the successive oxidative-oligomerization of radical intermediates. The formation of oligomers dramatically reduced the estrogenic activity of E2. Additionally, CC- Th Lac also exhibited high-efficiency metabolism capability toward E2 in the natural water and pig manure, with more than 94.4% and 91.0% of E2 having been metabolized, respectively. These findings provide a broad prospect for the clean biotechnological applications of Trametes hirsuta La-7 in estrogen-contaminated ecosystems.
研究领域:
环境生物学
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生物化学
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生态学
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产品关联
DOI
PubMed
高影响因子
ENVIRONMENTAL POLLUTION
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2023
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IF 8.9
Jie Liu,Kai Sun,Rui Zhu,Xun Wang,Michael Gatheru Waigi,Shunyao Li
Bisphenol A (BPA) is a ubiquitous endocrine disruptor that poses adverse human health risks. Herein, biotransformation kinetics, products, and mechanisms of BPA undergoing a laccase-producing Trametes hirsuta La-7 metabolism were for the first time reported. Strain La-7 could completely biotransform ≤0.5 mmol·L −1 BPA within 6 d in vivo . Notably, its extracellular crude laccase solution (ECLS) and intracellular homogenized mycelium (HM) only required 6 h to convert 85.71% and 84.24% of 0.5 mmol·L −1 BPA in vitro , respectively. The removal of BPA was noticeably hampered by adding a cytochrome P-450 inhibitor (piperonyl butoxide) in HM, disclosing that cytochrome P-450 monooxygenase participated in BPA oxidation and metabolism. BPA intermediates were elaborately identified by high-resolution mass spectrometry (HRMS) combined with 13 C stable isotope ratios (BPA: 13 C 12 -BPA = 0.25: 0.25, molar concentration). Based on the accurate molecular mass, isotope labeling difference, and relative intensity ratio of product peaks, 6 versatile metabolic mechanisms of BPA, including polymerization, hydroxylation, dehydration, bond cleavage, dehydrogenation , and carboxylation in vivo and in vitro , were confirmed. Germination index values revealed that inoculating strain La-7 in a BPA-contaminated medium presented no phytotoxicity to the germinated radish ( Raphanus sativus L.) seeds. In vivo , Mg 2+ , Fe 2+ , Fe 3+ , and Mn 2+ were conducive to BPA removal, but Cd 2+ and Hg 2+ significantly obstructed BPA elimination. Additionally, strain La-7 also exhibited high-efficiency metabolic ability toward estrone (E1), 17 β -estradiol (E2), and 17 α -ethinylestradiol (EE2), with more than 96.13%, 96.65%, and 100% of E1, E2, and EE2 having been converted, respectively. Our findings provide an environmentally powerful laccase-producing fungus to decontaminate endocrine disruptor-contaminated water matrices by radical polymerization and oxidative decomposition.
研究领域:
环境科学
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微生物学
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毒理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
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2023
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IF 5
Si Zhenyuan,Cai Yang,Zhao Lang,Han Lu,Wang Feng,Yang Xiaobing,Gao Xiangdong,Lu Meiling,Liu Wei
Abstract α-L-Arabinofuranosidases (Abfs) play a crucial role in the degradation of hemicelluloses, especially arabinoxylans (AX). Most of the available characterized Abfs are from bacteria, while fungi, as natural decomposers, contain Abfs with little attention given. An arabinofuranosidase ( Th Abf1), belonging to the glycoside hydrolase 51 (GH51) family, from the genome of the white-rot fungus Trametes hirsuta , was recombinantly expressed, characterized, and functionally determined. The general biochemical properties showed that the optimal conditions for Th Abf1 were pH 6.0 and 50°C. In substrate kinetics assays, Th Abf1 preferred small fragment arabinoxylo-oligosaccharides (AXOS) and could surprisingly hydrolyze di-substituted 2 3 ,3 3 -di-L-arabinofuranosyl-xylotriose (A 2,3 XX). It also synergized with commercial xylanase (XYL) and increased the saccharification efficiency of arabinoxylan. The crystal structure of Th Abf1 indicated the presence of an adjacent cavity next to the catalytic pocket which led to the ability of Th Abf1 to degrade di-substituted AXOS. The narrow binding pocket prevents Th Abf1 from binding larger substrates. These findings have strengthened our understanding of the catalytic mechanism of GH51 family Abfs and provided a theoretical foundation for the development of more efficient and versatile Abfs to accelerate the degradation and biotransformation of hemicellulose in biomass. Key points ThAbf1 from Trametes hirsuta degraded di-substituted arabinoxylo-oligosaccharide. ThAbf1 performed detailed biochemical characterization and kinetics. ThAbf1 structure has been obtained to illustrate the substrate specificity. Graphical abstract
研究领域:
生物化学
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酶学
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微生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
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