Pedosphere 27(3): 606--615, 2017
ISSN 1002-0160/CN 32-1315/P
©2017 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Biodegradation of phthalate esters by a newly isolated Acinetobacter sp. strain LMB-5 and characteristics of its esterase
FANG Yue1, ZHANG Lishuang1, WANG Jing1, ZHOU Ying2,YE Bangce1,2
1Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237 (China)
2 School of Chemistry and Chemical Engineering, Shihezi University, Xinjiang 832000 (China)
ABSTRACT
      Phthalate esters (PAEs) are extensively applied in industry, and they migrate to environment during the process of production, employ, and treatment and are difficult to be degraded in nature.However, some microorganisms could use them as the carbon source to growth. In this study, an Acinetobactersp.strain LMB-5, capable of utilizing PAEs, was isolated from a vegetable greenhouse soil. The degradation capability of strain LMB-5 was also investigated by incubation in mineral salt medium containing different PAEs, dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), and di-(2-ethylhexyl) phthalate (DEHP).The strain could grow well with DMP, DEP, DBP, and DEHP. When the concentration of DBP increased from 100 to 400 mg L-1, the half-life extended from 9.5 to 15.5 h.In the concentration range of DBP, the degradation ability of strain LMB-5 could be described by first-order kinetics. During the biodegradation of DBP, three intermediates, 1,2-benzenedicarboxylic acid,butyl methyl ester, DMP, and phthalic acid (PA) were detected, and the proposed pathway of DBP was identified. By analysis of bioinformatics, one esterase was cloned from the genome of LMB-5 and expressed in Escherichia coli. It displayed an ability to break the ester bonds of DBP. The enzyme exhibited maximal activity at pH 7.0 and 40 $^\circ$C with DBP as the substrate.It was activated by Cu2+ and Fe3+ and had a high activity in the presence of low concentrations of methanol or dimethylsulfoxide (each 10%, volume:volume).The Acinetobacter sp.strain LMB-5 may make a contribution to the remediation of soils polluted by PAEs in the future.
Key Words:  biological toxicity, degradation bacteria, di-n-butyl phthalate, enzymatic activity, hydrolase, soil pollution
Citation: Fang, Y., Zhang, L., Wang, J., Zhou, Y. and Ye, B. 2017. Biodegradation of phthalate esters by a newly isolated Acinetobacter sp. strain LMB-5 and characteristics of its esterase. Pedosphere. 27(3): 606-615.
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