J Gregory Zeikus

B.S., 1967, University of South Florida
M.S., 1968, Ph.D., 1970, Indiana University
Postdoctoral Associate, 1970-1972, University of Illinois

Research
Research in this laboratory is aimed at understanding microbial metabolism and the electrochemistry of energylinked chemical transformation reactions performed by bacteria in natural and industrial processes. The goals of the research program are to elucidate how cellular and molecular functions control microbial activity in pure and mixed cultures; and how these features can be manipulated in order to improve microbial fermentation or enzyme systems for the production of chemicals, ingredients and fuels from renewable resource substrates (i.e., biomass, starch, cellulose), simple inexpensive chemicals (i.e., CO, CH3OH, H2CO2), or wastes (industrial, municipal and agricultural). Fundamental and applied process research topics include: thermophiles and thermostable enzymes, enzymatic solubilization of biopolymers, production of organic alcohols or acids from starch and cellulose fermentations; methane formation from organic waste treatment; extremophiles and physiological adaptation to extreme stress; and synthesis of higher molecular weight fermentation products (i.e., acetic acid, butyric acid, long chain alcohols, amino acids and vitamins) from single-carbon substrates (i.e., methanol, carbon monoxide and H2CO2). The focus of the research program is on understanding both metabolic regulation of carbon and electron flow pathways in anaerobic bacteria and enzyme structure function relationships with an approach that combines the ecological, physiological, biochemical, genetic and bioengineering studies.

The use of biocatalysts (i.e., microbes and enzymes) in industrial processes has been greatly expanded by the application of microbial diversity and new bioengineering technologies including genetic engineering. These industrial bioprocesses involve the use of biocatalysts in: biochemicals and biomaterials production, drug synthesis and manufacture, sensors and diagnostics, food and feed production and waste treatment systems. Developing robust biocatalaysts that function under harsh physical chemical processing conditions is a real challenge that has recently been aided by using extremophiles and extremozymes as model systems for fundamental and practical understanding. Our research on extremophiles and extremozymes involves determining and applying rational design parameters for the control of biocatalyst stability, activity and chemical yield. Our work on the design and control of industrial biocatalysts includes the engineering of thermozymes by protein and genetic engineering techniques; microbial organic acid and alcohol fermentations by metabolic engineering of pathways and enzyme regulations; and anaerobic biodegradation granules by ecoengineering the performance of mixed microbial populations.