Isolation and identification of a 2,3,7,8-Tetrachlorodibenzo-P-dioxin degrading strain and its biochemical degradation pathway

Lina Qiu; Weiwei Zhang; Aijun Gong; Jiandi Li

doi:10.1007/s40201-021-00626-9

Isolation and identification of a 2,3,7,8-Tetrachlorodibenzo-P-dioxin degrading strain and its biochemical degradation pathway

J Environ Health Sci Eng. 2021 Feb 24;19(1):541-551. doi: 10.1007/s40201-021-00626-9. eCollection 2021 Jun.

Authors

Lina Qiu^{1

2}, Weiwei Zhang^{2

3}, Aijun Gong^{1

2}, Jiandi Li¹

Affiliations

¹ School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing, 100083 People's Republic of China.
² Beijing Key Laboratory for Science and Application of Functional Molecular and Crystalline Materials, University of Science and Technology Beijing, 100083 Beijing, China.
³ Basic Experimental Center for Natural Science, University of Science and Technology Beijing, Beijing, 100083 China.

Abstract

This study aims to find a high-efficiency degradation strain which can biodegrade the 2,3,7,8-Tetrachlorodibenzo-P-dioxin (2,3,7,8-TCDD). In this paper, a new fungus strain was isolated from activated sludge of Dagu Drainage River in Tianjin which was able to degrade 2,3,7,8-TCDD in the medium. Based on its morphology and phylogenetic analysis of its 18S rDNA sequence, the strain was identified as Penicillium sp. QI-1. Response surface methodology using central composite rotatable design of cultural conditions was successfully employed for optimization resulting in 87.9 % degradation of 2,3,7,8-TCDD (1 µg/mL) within 6 days. The optimum condition for degrading 2,3,7,8-TCDD was at 31℃ and pH 7.4. The biodegradation process was fitted to a first-order kinetic model. The kinetic equation was C_t=0.939e^{- 0.133t} and its half-life was 5.21d. The fungus strain degraded 2,3,7,8-TCDD to form intermediates, they were 4,5-Dichloro-1,2-benzoquinone, 4,5-Dichlorocatechol, 2-Hydrooxy-1,4-benzoquinone, 1,2,4-Trihydroxybenzene and β-ketoadipic acid. A novel degradation pathway for 2,3,7,8-TCDD was proposed based on analysis of these metabolites. The results suggest that Penicillium sp. QI-1 may be an ideal microorganism for biodegradation of the 2,3,7,8-TCDD-contaminated environments.

Keywords: 2,3,7,8-TCDD; Biodegradation; Degradation pathway; Kinetics; Penicillium sp..