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Phytotoxicity of pah, extra-heavy crude oil and its fractions in lactuca sativa: An integrated interpretation using a modified toxicity index

Abstract:

The pollution of ecosystems by toxic and carcinogenic hydrocarbons derived from petroleum is an environmental problem. Therefore, scientists have developed bioremediation to clean up contaminated sites with microorganisms that have the ability to degrade hydrocarbons. However, some are capable of generating more toxic metabolites when they biotransform these compounds. To detect the possible formation of toxic compounds, toxicity tests on germination and seedling growth of Lactuca sativa have been designed as a frame of reference. The aim of this work was to study the toxic effects of extra-heavy crude Carabobo and its saturated and aromatic fractions; three polycyclic aromatic hydrocarbons, phenanthrene, naphthalene and pyrene, and finally the evaluation of the possible toxic effect of biotreated hydrocarbons with Penicillium aculeatum (BM-83). It was demonstrated that low concentrations of naphthalene, phenanthrene, pyrene and saturated hydrocarbons, generated stimulus for growth in the seedlings of L. sativa. On the other hand, high concentrations of hydrocarbons mainly affected the growth of hypocotyls, which suggests the importance of using a modified toxicity index that considers the growth of the hypocotyl. The order of toxicity of hydrocarbons according to the IIF was naphthalene (100) > phenanthrene (65) > pyrene (64) > aromatic (27) > CEP (7) > saturated (1). The IIF allowed showing that the fungus BM-83 is able to biotransform hydrocarbons without generating compounds that are more toxic than the original.