Bioremediation of Oil Pollutants by Fungi Associated with Coastal Mangroves from Puerto Rico
Mangroves play an important ecological role in the coastal environment. They stabilize coastlines, reducing erosion from storm surges, waves, tides and currents. This ecosystem is highly vulnerable to pollution regularly exposed to petroleum hydrocarbons (PHCs) from motorboats such as waste gasoline, diesel and motor oil leakage. These compounds have stable ring structures difficult to degrade, hence harmful to the environment and even carcinogenic. The compounds found in the PHCs also accumulate in sediments of mangroves and because of their low solubility and hydrophobic nature it is difficult to eliminate them, thus persisting in the ecosystem. Nonetheless, lignolytic fungi have been found to produce extracellular enzymes capable of degrading these organic compounds. Therefore, the primary objective for this study is to isolate and characterize autochthonous fungi that can degrade PHCs. Twenty seven fungi specimens from mangrove leaves and soil samples were isolated in Potato Dextrose Agar (PDA). These were later inoculated in Congo Red Agar (MgSO4: 0.5g, NaNO3: [10mg/ml], H2KPO4: 0.5g, HK2PO4: 0.6g and Congo Red: [0.04mg/ml]) to determine their ability to degrade azoles. Only thirteen isolates showed growth in the media indicating possible PHC degraders. Molecular characterization was performed for six selected specimens corresponding to Talaromyces ruber, Trichoderma sp., Purpureocillium lilacinum, Aspergillus sp., Emericella sp. and Pichia guilliermondii. These fungi were inoculated in a motor oil waste liquid media (NaNO3, aged sea water and used motor oil) to determine their capacity to degrade PHCs. Biomass production was evaluated by dry weight after 21 days of growth. Preliminary results indicate T. ruber is the fastest strain in our samples so far.