Biodegradation of hydrocarbons from contaminated soils by microbial consortia: A laboratory microcosm study

Abstract

Background: Compounds derived from hydrocarbons are essential for industry and our daily life; however, accidents such as spills or leaks occur regularly, causing severe environmental impact. Therefore, bacteria isolated from an oil well were characterized to assess their potential in the degradation of hydrocarbons under individual and consortium treatments. Soil samples, from a well contaminated with hydrocarbons in Tabasco, Mexico, were collected. The biosurfactant, emulsifying capacity, hemolytic activity, ionic charge, and biofilm formation were analyzed.

Results: Most of the isolated strains belong to the genus Pseudomonas according to 16S rDNA sequencing. In general, emulsification percentages greater than 60% in the different substrates evaluated were observed. In addition, these strains can form biofilms, and those selected to integrate the microbial consortia present anionic surfactants. Three strains were selected to evaluate the degradation potential of soil contaminated with hydrocarbons from the same site where the bacteria were isolated in a microcosm. The microbial consortia degraded the contaminated soil more efficiently than the strains were evaluated alone, mainly the three bacteria consortia, with percentages greater than 80%.

Conclusions: This study shows that, despite belonging to the same species, bacterial strains’ metabolic capacity for the expression of surfactant compounds, emulsifiers, and the formation of biofilms are different. Furthermore, the more structured a community is, the greater the biodegradation process that occurs when bacteria act individually on the substrate. Therefore, this study demonstrates that strains of the same species integrated microbial consortia improve the bioremediation processes of hydrocarbons in contaminated soils.