Crude-oil degradation capabilities by microscopic fungi of deep-sea hydrothermal vents

Selected microscopic fungi from extreme marine ecosystems have unique capacities to degrade complex oil molecules, which confers them a growing interest in bioremediation. This study evaluated the oil-degrading capabilities of six fungal isolates from deep-sea hydrothermal vents. The response of the isolates to the presence of light crude oil (LCO) and heavy crude oil (HCO) was assessed through a tolerance bioassay, while their capabilities to degrade the oil as the sole carbon source were tested in a biodegradation bioassay. The assimilation of oil derivatives into fungal tissues was determined by their carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopes. The compositional changes in HCO after exposure to Aspergillus terreus and Penicillium miczynskii (isolate F) were assessed. All isolates grew in the presence of both oils in the tolerance bioassays, yet A. terreus, Aspergillus sydowii, and P. miczynskii (isolates E and F) showed enhanced growth when using crude oil as the sole carbon source. The δ¹³C was more enriched in the isolates than in the oil, suggesting they used it as a carbon source. The analysis of the oil exposed to fungal activity showed that fungi degraded medium and long-chain hydrocarbons. Particularily, P. miczynskii (F) showed a remarkable growth in the bioassays and the ability to degrade complex hydrocarbons, representing a promising bioremediation agent.