Preliminary study of microbial communities in soil contaminated with oil hydrocarbons from Icoana

Abstract

Soil contamination with crude oil or petroleum residues is worldwide the major problem occurred consequently to exploitation, transport and processing. The presence of hydrocarbons leads to increased quantities of carbon and imbalances in C:N ratio with consequences on microbial life from soil. A wide variety of edaphic microorganisms including bacterial and fungal species are known as hydrocarbon bio-degraders, contributing to soil decontamination. Research has been carried out to characterize the microbial communities in soil contaminated with oil hydrocarbons by an accidental spill from broken pipes in Icoana, Olt county. The results revealed important decrease in both bacterial and fungal counts under the impact of contaminant hydrocarbons as compared to non-contaminated soil, accompanied by biodiversity loss (SR2 values 1.49 for bacteria and 2.32 for fungi comparatively with 7.02 and respectively 3.27 in non-contaminated soil). Low levels of global physiological activity of microorganisms registered in contaminated soil and 2.34 times higher levels in non-contaminated soil. Changes in species composition of microbial populations indicated moderate similarity between bacterial species lists (SI=67) and important dissimilarity between fungal species lists (SI=16). Hydrocarbon utilizers from microflora included pseudomonads, bacilli and cosmopolitan fungal species from genera Cladosporium, Fusarium, Sporothrix in contaminated soil and Trichoderma, Cladosporium, Aspergillus, Penicillium in non-contaminated soil.