MOD Lab - Current Research

NanoSIMS Analysis

Working at the margins requires extremely high sensitivity and the application of a full suite of microbial and geochemical tools to sift through the noise and find signals of life in desolate places. High sensitivity can be achieved by using a nanoscale secondary ion mass spectrometer (NanoSIMS). This instrument allows you to view images of up to seven different individual ions simultaneously at nanometer resolution. Since microbes are micrometer sized, three orders of magnitude larger, this allows for subcellular imaging of microbes. This can be paired with a technique called stable isotope probing (SIP) where microbes are provided a buffet of potential food sources that have a unique tracer (a rare isotope abundance you would never find in nature) such that you can track if a food chosen by the microbe ends up incorporated into the cell based on the premise that they are what they eat. This combined approach of looking for very rare isotopes with high resolution (SIP-NanoSIMS) is perfectly suited to studying microbial life on the edge where signals of life could not be detected by any other means.

Habitability of Arid Soils

While seemingly unrelated desert soils and deep subsurface sediments share one major limitation – access to water. Water has been suggested as the “master variable” controlling soil microbial communities, but it remains unconstrained if this is due to physiological stress or solute supply. Our lab’s involvement in these projects is through an astrobiology lens, specifically with an eye toward Mars.

Funding: NASA Exobiology

Habitability of the Atmosphere

Classically, atmospheric-dwelling microbes are thought to be passively dispersed, without performing metabolic activities or mediating ecological interactions. However, recent work suggests that the atmosphere may be a true ecosystem: containing active resident and transient microbes that profoundly influence biology, chemistry, and climate globally. This project will test whether the atmosphere is indeed ‘a living, breathing ecosystem’.

Funding: Human Frontier Science Program

Exploring Ocean Worlds

From hydrothermal vents to the cool crust along abyssal planes, microbial life has found myriad mechanisms for survival in the ocean-derived fluids that travel through cracks in rocks on the ocean floor. However, it remains an open question what portion of this life is truly removed from the involvement with the surface world, specifically its potential nutrient sources. For example, hydrothermal vents are known to house microbes that can generate biomass and energy from carbon dioxide and methane readily available in vent fluids (dark carbon primary production). Yet, ready-made potential food sources also rain down from surface water and can be carried into the subsurface (light, or photosynthesis, derived organic carbon). By providing both types of carbon to marine microbes, we can observe their food preferences and the rates at which they use them. This second point is critical for understanding the microbial role in global carbon cycles, but is critically under constrained in subsurface fluids. This work also has implications for ocean worlds with planned or proposed missions such as Jupiter’s moon Europa.

Funding: NASA Exobiology