Award: OCE-1829680

The hydrothermal sediments of Guaymas Basin in the Gulf of California contain fresh petroleum that is produced from marine algae biomass under high temperature and pressure. These petroleum compounds (hydrocarbons) are a carbon source for microorganisms, and have over time selected for numerous specialized petroleum- and gas-degrading bacteria and archaea that thrive in these hydrothermal sediments. In addition, microscopic fungi, for example single-celled yeasts, have the ability to degrade petroleum hydrocarbons, but their presence and activity in Guaymas Basin has never been studied. Bacteria and fungi could also act together in a symbiotic fashion. Consequently, the major goals of this project are to isolate hydrocarbon-degrading marine fungi from Guaymas Basin, to identify specific hydrocarbon substrates that are used preferentially used and processed by these fungi, and to investigate their function within the hydrocarbon-driven Guaymas ecosystem. Since the Guaymas Basin sediments also contain numerous hydrocarbon-degrading bacteria and archaea, this project is also examining potential interactions of bacteria and fungi that promote hydrocarbon degradation, for example in co-culture under anaerobic conditions. My part of this collaborative project focuses on the isolation of hydrocarbon-degrading sulfate-reducing bacteria for use in co-culture experiments with fungi. We examined patterns in fungal community structure in Guaymas Basin sediments, and found that these patterns differ from those observed in the structure of bacterial and archaeal communities; at least in the surficial sediments, fungal communities are greatly influenced by sedimentation from the upper water column where they occur in parasitic association with planktonic algae. In the lab, many different marine fungi in Guaymas can be cultured from Guaymas Basin sediments (interestingly, most cultured isolates produce antibacterial secondary metabolites), but the uncultured diversity of fungi is vastly greater than what we could culture so far. In the sediments, fungi (by themselves and in association with bacteria) help to degrade the complex hydrocarbons that occur naturally in Guaymas Basin sediments. Last Modified: 10/12/2022 Submitted by: Andreas P Teske