Arbuscular mycorrhizal fungi from petroleum-impacted sites in the Polish Carpathians

Bioremediation by microorganisms is regarded as an efficient strategy for treating oil spills and wastes. Although mycorrhizal fungi do not degrade petroleum, they are a very good example of beneficial soil microorganisms that improve both the growth and vitality of plants and may enhance their bioremediation activity. In this work, arbuscular mycorrhizal fungi (AMF) were investigated in sites containing soil exposed to the long-term presence of petroleum. These sites are located in southern Poland (Carpathians), where remnants of commercial oil exploitation in the 19th century and natural petroleum seeps can be found. The mean concentrations of mineral oil and polycyclic aromatic hydrocarbons (PAH16) in the soil were 46473 mu g x g(-1) d.w. and 138 mu g x g(-1) d.w., respectively. Roots of collected petroleum-tolerant plants were analyzed using light microscopy and the associated AMF were identified by sequencing the 18S rRNA SSU genes. Most of these plants showed the presence of mycorrhizal colonization. 11 AMF phylotypes were identified: Acaulospora sp., Archaeospora sp., Claroideoglomus sp., Diversispora sp., Rhizophagus intraradices, R. iranicus; plus five groups that could not be unambiguously identified. The results of this study provide additional insight into the diversity of beneficial fungi that interact with plants which survive in a hostile environment. The data obtained are the first steps towards the application of well-adapted AMF to the bioremediation of hydrocarbon-polluted soils.