title: Biodegradation of the endocrine disrupter 4-tert-octylphenol by the yeast strain Candida rugopelliculosa RRKY5 via phenolic ring hydroxylation and alkyl chain oxidation pathways.
abstract: 4-(1,1,3,3-tetramethylbutane)-phenol (4-tert-OP) is one of the most prevalent endocrine disrupting pollutants. Information about bioremediation of 4-tert-OP remains limited, and no study has been reported on the mechanism of 4-tert-OP degradation by yeasts. The yeast Candida rugopelliculosa RRKY5 was proved to be able to utilize 4-methylphenol, bisphenol A, 4-ethylphenol, 4-tert-butylphenol, 4-tert-OP, 4-tert-nonylphenol, isooctane, and phenol under aerobic conditions. The optimum conditions for 4-tert-OP degradation were 30°C, pH 5.0, and an initial 4-tert-OP concentration of 30mgL-1; the maximum biodegradation rate constant was 0.107d-1, equivalent to a minimum half-life of 9.6d. Scanning electron microscopy revealed formation of arthroconidia when cells were grown in the presence of 4-tert-OP, whereas the cells remained in the budding form without 4-tert-OP. Identification of the 4-tert-OP degradation metabolites using liquid chromatography-hybrid mass spectrometry revealed three different mechanisms via both branched alkyl side chain and aromatic ring cleavage pathways.
authors.affiliation: Department of Life Sciences, National Central University, No. 300, Zhongda Rd., Zhongli District, Taoyuan City 32001, Taiwan.
authors.forename: Ranjith Kumar
authors.initials: RK
authors.lastname: Rajendran
authors.affiliation: Department of Life Sciences, National Central University, No. 300, Zhongda Rd., Zhongli District, Taoyuan City 32001, Taiwan.
authors.forename: Shir-Ly
authors.initials: SL
authors.lastname: Huang
authors.affiliation: Graduate Institute of Environmental Engineering, National Central University, No. 300, Zhongda Rd., Zhongli District, Taoyuan City 32001, Taiwan.
authors.forename: Chu-Ching
authors.initials: CC
authors.lastname: Lin
authors.affiliation: Department of Life Sciences, National Central University, No. 300, Zhongda Rd., Zhongli District, Taoyuan City 32001, Taiwan. Electronic address: kirschner@ncu.edu.tw.
authors.forename: Roland
authors.initials: R
authors.lastname: Kirschner
mesh_terms: D001673:Biodegradation, Environmental; D002175:Candida / Q000378:metabolism*; D002853:Chromatography, Liquid; D052244:Endocrine Disruptors / Q000378:metabolism*; D006207:Half-Life; D006863:Hydrogen-Ion Concentration; D006900:Hydroxylation; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D010636:Phenols / Q000032:analysis / Q000378:metabolism*
chemical_list: D052244:Endocrine Disruptors; D010636:Phenols; C105260:4-tert-octylphenol
keywords: Bioremediation; Endocrine disrupting chemicals (EDCs); Estrogenic activity; Proposed pathway; Surfactants