Nickel is a biologically active trace metal important to mammalian health, as are numerous obligately anaerobic bacteria which inhabit the microintestinal environment. This study centers on further resolving (i) the biochemical/biological nature of nickel in acetogenic bacteria and (ii) the autotrophic metabolism of this biological group. Specifically, the biochemistry and physiological function of the nickel enzyme carbon monoxide dehydrogenase will be further resolved and acetogenic hydrogenase will be purified and characterized. The regulation and intracellular localization of autotrophic enzymes will be studied in effort to gain insights into their physiological roles. Antibodies (rabbit) against key catalysts may be used as specific probes to aid in this elucidation. 14C tracer and product profile analyses will be conducted to study whole cell carbon flow and energetics of autotrophic vs. heterotrophic growth. Additionally, studies on recently discovered nickel proteins will be initiated to ascertain their potential physiological functions. Defined minimal media developed for the cultivation of acetogenic bacteria will facilitate studies on acetogenic nickel transport and trace metal requirements. Since acetogens and most of their enzymes are extremely sensitive to oxidation, all cultivation, purification, and analytical procedures will be conducted under strict anaerobiosis.