Microbial life in a liquid asphalt desert

Area of Science:

• Microbial Ecology
• Biogeochemistry
• Petroleum Science

Background:

• Pitch Lake, Trinidad and Tobago, is a natural asphalt reservoir formed by petroleum seepage.
• The asphalt residue is characterized by low water activity, recalcitrant carbon, and noxious compounds.
• This extreme environment hosts a unique microbial community.

Purpose of the Study:

• To investigate the microbial ecology and biogeochemistry of Pitch Lake.
• To characterize the microbial diversity and metabolic potential within the asphalt matrix.
• To establish Pitch Lake as a terrestrial analogue for extraterrestrial hydrocarbon environments.

Main Methods:

• Geochemical analysis of the asphalt column.
• Molecular taxonomic approaches (e.g., DNA sequencing) to identify microbial lineages.
• Comparison with microbial communities from other hydrocarbon-rich environments.

Main Results:

• An active microbial community (up to 10(7) cells/gram) of archaea and bacteria, including novel strains, inhabits Pitch Lake.
• Diverse, novel microbial lineages with potential for anaerobic hydrocarbon degradation were identified.
• Evidence for archaeal methane metabolism and anaerobic sulfur- and nitrite-oxidizing bacteria was found.
• Microbial diversity is unique compared to other natural asphalt and petroleum environments.

Conclusions:

• Pitch Lake harbors a unique and diverse microbial ecosystem adapted to extreme hydrocarbon conditions.
• The identified microbial lineages possess significant potential for mediating hydrocarbon degradation.
• Pitch Lake serves as a valuable terrestrial analogue for studying life in hydrocarbon-rich environments, including those on other celestial bodies like Titan.