Removal of High Concentrations Decachlorobiphenyl of Earthworm Eisenia fetida and its Symbiotic Bacteria in a Vermicomposting System

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 (H S and H P) with PCBs compared to a control sample without contaminant and the modi ed forest (F) and agricultural (A) soil in the laboratory with 100 mg L-1 PCB. For the analysis of 16S rRNA genes ampli ed from DNA extracted from the soils evaluated, the latest generation of Illumina Miseq and Sanger sequencing for the cultivable strains were detected. The bacteria identi ed as the most abundant bacterial phyla for H S and H P 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 identi ed 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 identi ed 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.

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

“…Likewise, no discernable differences between the different samples were determined in related to electrical conductivity (EC). It is known that the EC is related to the salinity content of the soil (Zenteno-Rojas et al 2019 ). The samples obtained in soil F had the highest EC value (0.076 dS m −1 ), this could be due to the high content of Ca 2+ and Mg 2+ ions that is common in soils obtained from tropical forests (regosols).…”

Biostimulation and Bioaugmentation of Soils Contaminated with Decachlorobiphenyl (PCB-209) Using Native Bacterial Strains Individually and in Consortia

“…The soil characteristics were determined in all of the evaluated treatments at the end of the bioaugmentation process (day 21) to analyze the changes produced between the treatments. The pH and electric conductivity (EC) were measured by using a digital pH meter, a Mettler Toledo ® (Columbus, OH, USA) Model S220 (New York, NY, USA), in a 1:10 (weight/volume) aqueous solution [15]. The soil organic matter (SOM) content, total carbon, and C:N ratio were analyzed according to AOAC methods [19].…”

“…In the same way, in previous works, we have contributed to the study of highly efficient alternatives for the elimination and degradation of PCBs in contaminated soils. We examined vermicomposting systems and symbiotic bacteria from the earthworm Eisenia fetida and found that large amounts of PCB-209 could be removed [15]. Likewise, rhizospheric and endophytic bacteria associated with the Ocimun basilicum plant had the ability to remove up to 500 mg/L of PCB-209 [16].…”

Biodegradation α-endosulfan and α-cypermethrin by Acinetobacter schindleri B7 isolated from the microflora of grasshopper (Poecilimon tauricola)

“…A. schindleri can be found in different environments and is seldomly used for biodegradation of pesticides. Some studies indicate that A. schindleri can biodegrade different chemicals such as polyhydroxyalkanoates (Boyandin et al 2012), organic pollutants decachlorobiphenyl (Zenteno-Rojas et al 2019) and acetate (Sigala et al 2017). The aim of this study is to biodegrade α-endosulfan and α-cypermethrin using A. schindleri B7 isolated from insect ora and to determine their degradation products.…”