Evidence is mounting that the extraordinary metabolic and phylogenetic diversity of microorganisms is the result of several billion years of co-evolution with geologic processes. Investigating the intimate couplings of geochemistry and microbiology will become an even greater focus of geologic research in the foreseeable future. Among the best and most exciting sites to investigate the bio-geo interface are shallow marine hydrothermal ecosystems; they are ubiquitous, geochemically and microbiologically highly diverse, readily accessible for even complex investigations, and understudied compared to their deep-sea and continental counterparts. My primary career interests are understanding the geochemical constraints on metabolic diversity and investigating the role that microorganisms play in controlling their chemical environment. A crucial link between these two processes ? and between microbiology and geochemistry in general? is the availability of chemical energy sources. Quantifying the geochemical energy for thermophilic archaea and bacteria is at the core of my future studies. I have developed an integrated plan for research and education activities that will build a foundation for a long-term academic career. The plan includes expanding geobiology and geochemistry at Washington University through innovative course offerings and hands-on mentoring of graduate and undergraduate students. New courses, which seek to address several identified weaknesses in the curriculum, include a field/lab class in geobiology, a writing intensive course in the natural sciences, and multidisciplinary seminars that cover topics of exceptional and timely interests. The educational component proposed here also seeks to provide several extra learning opportunities (through Science Clubs) in low-income, urban area elementary schools; the ultimate challenge is to eliminate the "achievement gap" that exists between groups of students. This activity will be coordinated with established public outreach programs, teachers and volunteers at various K-5 schools, and numerous local science and nature centers. My new research directions in microbial geochemistry include 1) designing geochemically realistic growth media to culture heretofore "unculturable" thermophiles in hydrothermal ecosystems; 2) determining in situ energy-yields for an array of redox processes in vent environments, including the oxidation and fermentation of organic compounds and the conversion of Arsenic-bearing compounds; and 3) going "inside the cell" to quantify the free energies of common and central biochemical pathways as a function of temperature and pressure, both catabolic (energy-producing) and anabolic (biosynthesis) reaction networks. The approaches combine fieldwork (in situ measurements, sampling), analytical chemistry (aqueous solutions, gases, minerals), experimental microbiology (thermophile culturing, gene surveys), and quantitative modeling (reaction energetics, estimation of thermodynamic properties). The overall objectives are to generate quantitative, predictive, and comprehensive models of the biogeo interface in hydrothermal systems and to develop the scientific tools needed to test, guide, and improve our understanding of global biogeochemical processes.
