Taxonomic and functional characterization of the microbial community involved in the process of natural attenuation of jet fuel-contaminated soil

Author(s)

Kelly Johanna Hidalgo Martinez

• Document type: Master's Dissertation
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2019-08-02

Examining board members

Marcelo Falsarella Carazzolle; Cristina Rossi Nakayama

• Advisor: Valéria Maia Merzel

Abstract

Natural attenuation represents all process that govern contaminant mass removal in the environment, including microbial-mediated degradation. Although this process is intrinsic to the soil and aquifer microbial community, its rate and efficiency depend on multiple factors, including the abundance of microorganisms and their functional diversity for degrading these pollutants. This study aimed to characterize the microbial taxonomic and functional diversity in different depths of soils and in situ microcosms (BACTRAP®s) amended with aromatic hydrocarbons (Benzene, Toluene and Naphthalene) from a jet-fuel plume of an oil refinery located in Paulínia-SP. Microbial communities were characterized using 16S rRNA gene amplicon and metagenome "shotgun" Illumina high throughput sequencing. Results indicated that Proteobacteria, Actinobacteria and Firmicutes were the most dominant phyla (~98%), with Sphingomonadaceae, Propionibacteriaceae and Enterobacteriaceae as the predominant families in contaminated soils. Meanwhile, in benzene and toluene BACTRAP®s the phyla Firmicutes and Proteobacteria accounted for about 90% of total community members, with Peptococcaceae and Geobacteraceae as the main families. In the naphthalene BACTRAP®, members of the SR-FBR-L83 family (Order Ignavibacteriales, phylum Bacteroidetes) accounted for almost 80% of bacterial community. Functional annotation of soil metagenomes showed that only soil sample L62, located in the plume border and with the lowest BTEX concentration, has metabolic potential to degrade hydrocarbons aerobically via phenol and catechol pathways. On the other hand, the BACTRAP®s allowed the enrichment of bacteria known to be hydrocarbon degraders as well as the genes and metabolic pathways involved in anaerobic aromatic degradation. Specifically, fumarate addition is suggested as the main mechanism for hydrocarbon activation in toluene anaerobic degradation. Also, evidences of methylation, hydroxylation and carboxylation as activation mechanisms for the benzene anaerobic conversion were found. Microcosm samples showed metabolic potential to oxidize aromatic hydrocarbons coupled to anaerobic respiration using nitrate, ferric oxides and sulfate. The binning approach allowed to reconstruct ten genomes and two of them (Pelotomaculum propionicicum e Geobacter sp.) are suggested as the main actors in the degradation process at the contaminated plume. We propose that the microbiota in this BTEX plume groundwater has metabolic potential to degrade benzene and toluene by a syntrophic process between members of the families Geobacteraceae and Pelotomaculum, coupled to nitrate, iron and/or sulfate reduction (AU)

• FAPESP's process: 17/16611-0 - Quantification of microorganisms involved in the natural attenuation process of kerosene-contaminated soils
• Grantee: Kelly Johanna Hidalgo Martinez
• Support Opportunities: Scholarships in Brazil - Master