This research describes the changes in cell morphology of Azotobacter vinelandii cells cultured in dialyzed soil medium. This particular culture medium was assumed to provide the bacteria with an environment similar to their natural habitat, the soil.

The objectives of this research were to identify the form of Azotobacter as it exists in situ in the soil; to compare its resistance to that of laboratory grown cysts typical of those described in the literature; and to compare its resistance to that of cells grown on dialyzed soil agar. In addition, the morphology of the cells grown on dialyzed soil agar was examined by light and electron microscopy and then compared to the cysts grown on n-butanol Burk's medium. Dipicolinic acid and oxygen uptake rate were measured in cysts and on cells grown on dialyzed soil agar in order to determine whether the cells grown on dialyzed soil agar were endospores or other dormant form and also to measure the respiratory quotient in these cells.