The impact of pollutant as selection pressure on conjugative transfer of dioxin-catabolic plasmids harbored by Rhodococcus sp. strain p52.

Gang Zhao,Meng Chen,Li Li,Yanan Wu,Xu Wang

doi:10.1007/s11356-021-15682-9

Gang Zhao, Meng Chen + Show 3 more

Open Access

https://doi.org/10.1007/s11356-021-15682-9

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Abstract

Plasmid-mediated bioaugmentation has potential application in the cleanup of recalcitrant environmental pollutants. In this study, we examined the influence of various contaminants (in different categories or different amounts) as a selection pressure on the spread of catabolic plasmids within an activated sludge bacteria community bioaugmented with Rhodococcus sp. strain p52 harboring pDF01 and pDF02. The distinguishable genera of transconjugants were isolated under the stresses of phenanthrene, dibenzothiophene, and dibenzo-p-dioxin. The three contaminants exerted different degrees of influence on the activated sludge bacteria bearing the catabolic plasmids. The relatively high ratios of transconjugant-bearing catabolic plasmids were detected in the reactor fed with dibenzo-p-dioxin. As dibenzo-p-dioxin from 10 to 80 mg/L was fed into the reactors, the ratios of transconjugant-bearing catabolic plasmids increased. Additionally, levels of ROS and extracellular LDH of activated sludge bacteria in the contaminants-fed reactors increased, comparing with that in the control reactor, indicating that the contaminants exerted toxicity which promoted the cell membrane permeability of the activated sludge bacteria. Our study provides a characterization of the recalcitrant contaminants as a selection pressure that can modulate catabolic plasmid transfer during genetic bioaugmentation for the removal of contaminants.

Highlights

The escalating rate of industrialization has led to the release of various recalcitrant organic compounds into the environment during the past century
We examined the influence of various contaminants as a selection pressure on the transfer of catabolic plasmids within an activated sludge bacteria community bioaugmented with Rhodococcus sp. strain p52 harboring pDF01 and pDF02
Bioaugmentation is operated in two nuanced approaches: inoculating efficient degrading strains to dominate the degradation of pollutants or introducing mobile genetic elements (MGEs) to disseminate catabolic ability to indigenous bacterial populations (Carlos et al 2017)

Summary

Introduction

The escalating rate of industrialization has led to the release of various recalcitrant organic compounds into the environment during the past century Among these compounds, persistent organic pollutants comprise one of the most notorious groups, as they include polychlorinated dibenzodioxins, polychlorinated dibenzofurans, and polychlorinated biphenyls (Kulkarni et al 2008; Urban et al 2014). Environmental conditions, including biotic and abiotic factors, can influence genetic bioaugmentation These factors include the morphological and physiological characteristics of donor cells, the ratio and phylogenetic relatedness of donors and recipients, temperature, pH, and the features of contaminants (Alderliesten et al 2020; Carlos et al 2017; Shintani et al 2017; Stallwood et al 2005)

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