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

TATARIN, ANA SILVIA; SADAÑOSKI, MARCELA ALEJANDRA; FONSECA, MARÍA ISABEL

Congreso; SAIB-SAMIGE Joint Meeting 2020 ? Online; 2020

Polychlorinated biphenyls (PCBs) are exceptionally stable organic pollutants which their widespread distribution in terrestrialecosystems is now well documented worldwide. Biostimulation is an economical process for the removal of pollutants whichis based on the addition of nutrients and other supplementary components to the native microbial population to inducepropagation at a hastened rate. The rapid advancement of molecular ecological methods has facilitated the study of microbialstructure analysis without the bias introduced by cultivation. This study was aimed at assessing the impact of sugarcane bagasseon the bacterial diversity in soil contaminated with PCBs. Soil samples (48 g) were spiked with transformer oil contaminatedto reach 69.547 ± 9.799 μg/g of PCBs. The biostimulation (BE) set included soil samples mixed with sterilized sugarcanebagasse prepared to reach a final soil: sugarcane bagasse mass ratio of 3:1 (w/w). Non-amended soil (containing only distilledwater and PCBs) was used to verify natural attenuation (NA). All the experiments were performed in triplicate under nonsterile 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 andpyrosequencing process: PCR, amplicon library construction, and sequencing. Primers 515F (5'-GTGCCAGCMGCCGCGGTAA-3'), y 806R (5'-GGACTACHVGGGTWTCTAAT-3') were used to amplify the V1?V3 andV4 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 wereseparated by primers and adapters and then trimmed. Quality control of the reads, before and after trimming, was performedusing FastQC software version 0.11.2. Forward primer sequences were aligned to the Silva database reference alignment v102. Sequences outside the most represented alignment space were removed. Chimeras were also removed. OTUs wereclassified using the Silvaseed database v. 132 using 88% minimum identity with the query sequence. Taxonomic profilegraphics were performed in RStudio Version 1.2.5033 with the Phyloseq package. Taxonomic profiles of the bacterialcommunities at phylum level in BE soil showed they were dominated by Proteobacteria and Firmicutes, followed byAcidobacteria and Actinobacteria. However, in NA treatment, Firmicutes phylum was observed in abundance followed byProteobacteria. The number of bacterial communities at the genus level in BE showed they were more abundant than NAwhich demonstrated that this treatment could be promissory to bioremediation strategies.