Investigation of the microbiota and microbial processes involved in the anaerobic degradation of oil in Brazilian reservoirs

Abstract

Microbial biodegradation of oil in reservoirs has attracted the attention of researchers worldwide due to the alterations caused in oil properties with economic losses in the subsequent petroleum extraction and refining steps. The occurrence of biodegradation in oil reservoirs was mainly attributed to aerobic bacterial degradation of hydrocarbons. However, more recent hypotheses suggest that anaerobic degradation processes dominate these environments, despite the low reaction kinetics and the uncertainty about the prevalent degradation process in oil reservoirs. Current knowledge about the microbial diversity and metabolic processes involved in biodegradation in reservoirs is still limited, mainly due to the difficulty in recovering the complex microbial community present in such extreme environments. This project aims to assess the composition of the microbiota by a comparative analysis of biodegraded and non-biodegraded oil reservoirs using 16S rRNA gene libraries, and the mechanisms driving the petroleum degradation process through anaerobic microcosm assays. The microcosms will allow to monitor the microbial diversity, gene expression and the ability to remove hydrocarbons under different physicochemical conditions. These results will confirm if the methanogenic degradation of oil is actually prevalent or if it is dependent on the geographic location, geological history or physical-chemical conditions of the reservoir. The data obtained will certainly help to elucidate the most likely mechanisms of hydrocarbons degradation in Brazilian reservoirs.