Effects of pentachlorophenol on the bacterial denitrification process

Bairen Yang,Aihui Chen

doi:10.1080/09542299.2016.1212675

Bairen Yang, Aihui Chen

Open Access

https://doi.org/10.1080/09542299.2016.1212675

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Abstract

The use of pentachlorophenol (PCP) was banned or restricted in many countries worldwide because of its adverse influences on the ecological environment and humans. However, the potential disrupting effects of PCP on denitrifying microorganisms have warranted more analysis. In this study, the impacts of PCP on denitrification were investigated by using Paracoccus denitrificans as a model denitrifying bacterium. Compared with the control, the presences of 10 and 50 μM of PCP were found to significantly decrease the denitrification efficiencies from 98.5 to 87.2% and 68.7%, respectively. The mechanism studies showed that PCP induced the generation of reactive oxygen species, which decreased the vital enzymes activities related to glycolysis process, causing the disturbance of the metabolism of P. denitrificans utilizing carbon source (glucose) and the growth of the cell, and subsequently the generation of electron donor (NADH) for denitrification via NAD+ reduction was severely depressed. Further studies indicated that PCP also decreased the genes expression of several key enzymes responsible for denitrification, such as napA of nitrate reductase (NAR), nirS of nitrite reductase, norB of nitric oxide reductase, and nosZ of nitrous oxide reductase; however, there was only the enzyme activity of NAR was remarkably inhibited.

Highlights

Pentachlorophenol (PCP), a man-made halogenated aromatic compound, has been listed as a priority pollutant by the U.S Environmental Protection Agency for its persistence, toxicity, bioaccumulation, and potential human carcinogenicity.[1]
Nitrate reduction process of P. denitrificans was significantly inhibited by PCP at the dose investigated in this study (p < 0.05)
The exposure of PCP to P. denitrificans induced the generation of reactive oxygen species (ROS), which decreased the key enzymes activities related to glycolysis process, caused the disturbance of the metabolism of glucose utilization and the cell growth, and subsequently disturbed the generation of electron donor (NADH) for denitrification via NAD+ reduction

Summary

Introduction

Pentachlorophenol (PCP), a man-made halogenated aromatic compound, has been listed as a priority pollutant by the U.S Environmental Protection Agency for its persistence, toxicity, bioaccumulation, and potential human carcinogenicity.[1] It was used worldwide as agricultural pesticide, herbicide, wood preservative, and broadspectrum biocide,[2] as well as substance in total and bleaching effluent of pulp and paper mill industry.[3] the use of PCP has been banned or restricted in many countries since 1980s for its endocrine disrupting effects on the ecological environment and humans,[4] recently, it was still detected in various samples such as water, soil, sediment, aquatic organism, and human.[5,6,7]. It was reported that the annual national output of PCP has reached approximately 3000 tons in2003,[8,9]with there-emergence of schistosomiasis in the traditional epidemic areas.[10] The increased manufacture and application of PCP likely has resulted in more environmental release. The released PCP might influence the activity of environmental microorganisms

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