BTEX degradation by fungi

Aromatic hydrocarbons such as benzene, toluene, ethylbenzene and xylenes (BTEX) are environmental pollutants that cause serious problems in groundwater, in surface water and in soil. Specifically, the coastal area of Bourgas bay (Bulgarian Black Sea coast) is very vulnerable to such pollution as the large petrochemical industry situated there poses a continuing threat to the environment. The potential for degradation of BTEX by fungi was studied. Two fungal strains were used in the experiments carried out in a batch reactor. The fungi were isolated from gasoline-polluted sites and were identified as deuteromycetes belonging to the Cladophialophora (CPH) and Cladosporium (CS) genera. It was found that neither of the fungal strains was able to degrade benzene. Ethylbenzene was easily degraded in all cases; o- and m-xylene were fully degraded by Cladophialophora sp. both as single substrates and in mixtures with toluene, whereas Cladosporium sp. was able to degrade them fully in mixtures with toluene only. p-Xylene was only partially degraded in all tests; however, the experiments with Cladosporium sp. showed better results compared to those with Cladophialophora sp. in this particular case. Ethylbenzene, o- and m-xylene negatively affected toluene removal rate of both fungal strains, which suggests possible competitive substrate interactions. In general, the results obtained with Cladophialophora sp. were better than those with Cladosporium sp., except in the case of p-xylene degradation.