The long term goal of this project is to elucidate the role of bacteria in the manganese cycle in nature. The work immediate objective focuses on the role of bacteria in reducing manganese. In laboratory studies with pure cultures, the mechanisms by which bacteria reduce manganese will be investigated. Using these pure cultures, and enrichments (mixed cultures) from a variety of environments, the PI will also develop methods for distinguishing biological from (strictly) chemical reduction, and for charact- erizing the different types of biological Mn reduction. Finally, he will apply these methods to the study of Mn reduction in the field, both in fresh water (Oneida Lake, N.Y.) and marine (Black Sea) environments. Mechanistic studies will begin with strain SK13sp, a marine Bacillus that is a potent reducer of manganese. These studies will focus on isolation and identification of the extracellular Mn reductant produced by the cells. Concomitant with these studies, Nealsen will be characterizing other pure cultures, and beginning detailed analyses of other mechanisms. Development of field methods will focus on identifying mechanisms of Mn reduction, using analogues, inhibitors, and poisons. These methods will be tested in Oneida Lake, in Saanich Inlet, B.C. by Dr. B. Tebo, and used for field work in the Black Sea in 1987.
