The Amend Lab

The Amend Lab is a research group at the University of Southern California studying microbial geochemistry — from the continental and marine subsurface biosphere to astrobiology, the origin of life, carbon cycling, and bioenergetics. The lab was led by Professor Jan Amend of Earth Sciences and Biological Sciences, who also directed C-DEBI.

Dr. Jan Amend passed away on February 1, 2024. His lab has appreciated the outpouring of support from the community, and projects are underway to honor his legacy and achievements. He is sorely missed.

The Amend Laboratory has long been a hub for interdisciplinary research in microbial geochemistry, bridging the gap between Earth sciences and biological sciences. Based at the University of Southern California, the group has explored how microorganisms interact with their chemical environments across a stunning range of settings, from sunlit surface waters to the lightless fractures of the deep continental crust. This work rests on the principle that life, at its most fundamental level, is a series of energy-harvesting chemical reactions, and that understanding those reactions can reveal where and how microbes thrive.

A central theme of the lab's research has been the deep subsurface biosphere, one of the largest and least understood habitats on Earth. Vast populations of microorganisms live buried in marine sediments and within the rocky basement of the continents, often cut off from the surface world for millions of years. By studying the geochemical conditions that sustain these communities, researchers have gained insight into how life persists under extreme energy limitation, cycling carbon, nitrogen, and sulfur at rates so slow they challenge the very definition of metabolic activity.

Bioenergetics provides the theoretical backbone for much of the laboratory's work. Every microbial cell must capture energy from its surroundings to grow and reproduce, and the amount of energy available in a given environment dictates which metabolic strategies are viable. By combining thermodynamic calculations with field measurements of dissolved gases, ions, and minerals, the group has mapped the energetic landscapes of hydrothermal vents, subseafloor aquifers, and terrestrial hot springs, revealing the invisible boundaries that shape microbial ecosystems.

The origin of life remains one of science's most profound open questions, and the Amend Lab has contributed to this frontier through the lens of geochemistry. By examining how simple molecules could have assembled into self-replicating systems on the early Earth, the research connects the abiotic chemistry of minerals and water with the emergence of biology. Hydrothermal environments, where warm, mineral-rich fluids mix with seawater, have been of particular interest as plausible cradles for the first living cells.

Astrobiology extends the lab's reach beyond our own planet. The same geochemical principles that govern microbial life in Earth's subsurface can be applied to other worlds, such as the icy moons of Jupiter and Saturn or the subsurface of Mars. By identifying the minimum energy requirements for life and the chemical signatures that microbes leave behind, researchers help refine the search for biosignatures and guide the development of instruments destined for future planetary missions.

Carbon cycling in the marine subsurface represents another major research thrust. Organic matter that settles to the seafloor becomes buried and slowly degraded by microbial communities over geological timescales. Understanding the rates and pathways of this degradation is essential for modeling the global carbon cycle and predicting how deeply buried carbon reservoirs respond to environmental change. The lab's work has illuminated the microbial players and chemical reactions that govern this slow, subterranean carbon pump.

Education and mentorship have been integral to the laboratory's identity. Over the years, postdoctoral scholars, graduate students, and undergraduate researchers have trained in the group's methods, learning to combine fieldwork, laboratory experiments, and computational modeling. Many alumni have gone on to establish independent research programs at universities and institutions around the world, carrying forward the intellectual tradition of rigorous geochemical inquiry and collaborative, curiosity-driven science.

The broader significance of microbial geochemistry extends into practical realms, from understanding the fate of contaminants in groundwater to assessing the feasibility of subsurface energy storage. Microbes mediate reactions that can immobilize toxic metals, generate or consume greenhouse gases, and alter the porosity of rock formations. By revealing the rules that govern these processes, the research provides a foundation for informed stewardship of the planet's hidden environments.