A STUDY OF LARGE BODIES IN AZOTOBACTER AGILE

Abstract

Balloon forms and other morphologically abnormal cells of Azotobacter agile M.B. 4.4 have been observed every time that cells were placed on nutrient agar or soil extract agar. Unlike encysted vars. of Azotobacter, these peculiar shapes did not occur in A. agile when grown on a nitrogen-free medium, not even in very old cultures. Studies by single cell isolation and by observation of living cells revealed high viability in these abnormal bacteria. Attempts to check serological differences between regular and bizarre forms failed, since antibodies to any species of Azotobacter could not be produced in any of the animals used. Nuclear-staining procedures revealed several chromatinic units in normal cells. Since the chromatinic units were small, and since there was no definite pattern of change of these units when giant cells were formed, no conclusion was drawn as to their role in large body formation. The presence of large body forms in nature makes it difficult to explain their existence merely as degenerated cells.