Polysaccharide accumulation in the cell division defective mutant, Escherichia coli 15T-R1

The low temperature dependent cell division defective mutant, Escherichia coli 15T-R1, displays a wide range of cell lengths (2 to 500 micrometer) in late logarithmic phase cultures grown at 24 degrees C. When these cells were stained with a periodic acid-Schiff technique and viewed under light microscopy, polysaccharide accumulations appeared as discretely stained areas at the poles, and at sites throughout the cytoplasm of elongated cells. A statistical analysis of the relationships between the size of stained areas and cell size, indicated that the total amount of polysaccharide increased with increasing cell length. This occurred both by an increase in size of existing polysaccharide-stained areas and by the creation of new area. Interestingly, over a wide range of cell size, the ratio of cell volume occupied by polysaccharide to total cell volume remained nearly constant with a mean of about 0.16. These data suggest the existence of a homeostatic mechanism for regulating polysaccharide concentration during elongation.