IMPACT OF SUGARCANE BAGASSE ON THE BACTERIAL DIVERSITY IN A SOIL CONTAMINATED WITH PCBs

TATARIN AS; SADAÑOSKI MA; FONSECA, MI.

Simposio; LVI SAIB Meeting ? XV SAMIGE Meeting; 2020

Polychlorinated biphenyls (PCBs) are exceptionally stable organic pollutants which their widespread distribution in terrestrial ecosystems is now well documented worldwide. Biostimulation is an economical process for the removal of pollutants which is based on the addition of nutrients and other supplementary components to the native microbial population to induce propagation at a hastened rate. The rapid advancement of molecular ecological methods has facilitated the study of microbial structure analysis without the bias introduced by cultivation. This study was aimed at assessing the impact of sugarcane bagasse on the bacterial diversity in soil contaminated with PCBs. Soil samples (48 g) were spiked with transformer oil contaminated to reach 69.547 ± 9.799 μg/g of PCBs. The biostimulation (BE) set included soil samples mixed with sterilized sugarcane bagasse prepared to reach a final soil: sugarcane bagasse mass ratio of 3:1 (w/w). Non-amended soil (containing only distilled water and PCBs) was used to verify natural attenuation (NA). All the experiments were performed in triplicate under non-sterile conditions and incubated 90 days in darkness at 25 ± 1 °C, deionized water was added periodically to keep 75% (w/w) moisture content constant. Genomic DNA from soil was extracted using NucleoSpin® soil kit (Biocientífica SA, ARGENTINA) according to manufacturer?s instructions and sent to Macrogen Inc. (Seoul, Republic of Korea) for PCR and pyrosequencing process: PCR, amplicon library construction, and sequencing. Primers 515F (5'-GTGCCAGCMGCCGCGGTAA-3'), y 806R (5'-GGACTACHVGGGTWTCTAAT-3') were used to amplify the V1?V3 and V4 region of the bacterial 16S rRNA gene. Data analysis was performed with Mothur v.1.22.2. It was used to denoise, trim, filter and align sequences, find chimeras, assign sequences to operational taxonomic units. Quality-filtered sequences were separated by primers and adapters and then trimmed. Quality control of the reads, before and after trimming, was performed using FastQC software version 0.11.2. Forward primer sequences were aligned to the Silva database reference alignment v 102. Sequences outside the most represented alignment space were removed. Chimeras were also removed. OTUs were classified using the Silvaseed database v. 132 using 88% minimum identity with the query sequence. Taxonomic profile graphics were performed in RStudio Version 1.2.5033 with the Phyloseq package. Taxonomic profiles of the bacterial communities at phylum level in BE soil showed they were dominated by Proteobacteria and Firmicutes, followed by Acidobacteria and Actinobacteria. However, in NA treatment, Firmicutes phylum was observed in abundance followed by Proteobacteria. The number of bacterial communities at the genus level in BE showed they were more abundant than NA which demonstrated that this treatment could be promissory to bioremediation strategies.