Abstract
The effect of manganese ion on promoting both the growth rate and cell yield of Agrobacterium tumefaciens in a synthetic medium containing sucrose as a sole source of carbon and energy was shown. In the experiments elucidating the effect of manganese ion, Mn2+, on cell yield from a point of growth energetics, following results were obtained. (1) On carbon balance during the culture, all carbons of sucrose consumed were recovered in the products, such as 3-ketosucrose, carbon dioxide and bacterial cells; (2) on the chemical composition, there was little difference in the cells grown in a medium with and without manganese ion, and it was also found that 90% or more of the dry cells was composed of protein, polysaccharide, lipid, RNA and DNA; and (3) the energy balance at logarithmic growth phase was calculated under the assumptions that energy is required for the synthesis of cellular macromolecules and for the active transport of sucrose from the medium, and that energy is derived from the oxidation of sucrose to 3-ketosucrose and carbon dioxide. In the absence of manganese ion in the medium, the efficiency of ATP for growth was calculated to be 22.6%, whereas by the addition of manganese ion at a concentration of 10-5M the efficiency was raised to 78.0%. From these results it can be inferred that manganese ion makes tight the coupling of ATP consumption with the growth of Agr. Tumefaciens.
