Structure and diversity of native bacterial communities in soils contaminated with polychlorinated biphenyls

Adalberto Zenteno-Rojas,Daniel Castañeda-Valbuena,Rocío Meza-Gordillo,Miguel Ángel Vences-Guzmán,Clara Ivette Rincón-Molina,Reiner Rincón-Rosales,Juan José Villalobos-Maldonado,Esperanza Martínez-Romero,Víctor Manuel Ruíz-Valdiviezo

doi:10.1186/s13568-020-01058-8

Abstract

Persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) are a group of high-risk synthetic substances for human and environmental health. Currently, the study of sites contaminated by the spillage of equipment PCBs containing have been considered targeted areas for the study of bacterial communities with potential for PCBs degradation. There in isolation of bacterial strains is vital for use in biodegradable processes, such as bacterial bioaugmentation, which accelerates the development of phenomena such as natural attenuation of contaminated sites. The objective of this study was to assess biodiversity of bacteria contained in anthropogenic contaminated soils (HS and HP) with PCBs compared to a control sample without contaminant and the modified forest (F) and agricultural (A) soil in the laboratory with 100 mg L−1 PCB. For the analysis of 16S rRNA genes amplified from DNA extracted from the soils evaluated, the latest generation of Illumina Miseq and Sanger sequencing for the cultivable strains were detected. The bacteria identified as the most abundant bacterial phyla for HS and HP soil was Proteobacteria (56.7%) and Firmicutes (22.9%), which decreased in F and A soils. The most abundant bacterial genera were Burkholderia, Bacillus, Acinetobacter, Comamonas and Cupriavidus. Several species identified in this study, such as Bacillus cereus, Burkholderia cepacia, Comamonas testosteroni and Acinetobacter pittii have been reported as PCBs degraders. Finally, by means of a principal component analysis (PCA), a correlation between the physical and chemical characteristics of the soils in relation to the relative abundances of the bacteria identified was obtained. The C/N ratio was directly related to the control soil (without contaminant), while SOM maintained a relationship with F and A soils and the bacterial abundances were directly related to Hs and Hp soils due to the presence of aroclor 1260. Bacteria with the ability to tolerate high concentrations of this pollutant are considered for future use in biostimulation and bioaugmentation processes in contaminated soils.

Highlights

Polychlorinated biphenyls (PCBs) form a family of 209 congeners characterized by their chemical properties for use in industrial and commercial activities, such as electrical equipment (Furukawa and Fujihara 2008)
Soil characteristics The physicochemical analysis allowed to determine that there are significant variations between the different parameters evaluated in anthropogenic soils contaminated with PCBs compared to agricultural (A) and forest (F) soils that were enriched with the pollutant askarel (Table 1)
In the case of pH, this proved to be more acidic in soils collected at sites Hs and Hp, where there was a high concentration of PCBs, while in forest soils and in agricultural soils, the pH was slightly alkaline

Summary

Introduction

Polychlorinated biphenyls (PCBs) form a family of 209 congeners characterized by their chemical properties for use in industrial and commercial activities, such as electrical equipment (Furukawa and Fujihara 2008). PCBs mixtures are used mostly in the electrical industry, in equipment such as thermostats, condensers and in light transformers, where they constitute the main component (> 70%) of the oils used in this equipment as thermal insulators These oils are called askareles and are composed of synthetic fluid, chlorobenzoates and PCBs (Hu and Hornbuckle 2010). Most natural ecosystems and living organisms have been exposed to PCBs for several decades (Tehrani and Van 2014), so the elimination of PCBs accumulated in ecosystems have been an environmental problem at a global level, this challenge pursues the search for biological processes for their elimination (Robertson and Hansen 2015) These should include naturally occurring biodegradation processes together with added microbial communities able to survive in the presence of such toxic compounds (Matturro et al 2015). The aims of this study were investigate the diversity and abundance of bacteria in soils contaminated with polychlorinated biphenyls and correlate the characteristics of the soil and bacterial communities

Objectives

Methods

Results

Conclusion