Fragmentation of Some Gliding Bacteria During the Growth Cycle

As similar relative size distributions were obtained when populations of gliding bacteria were studied with the light microscope or Coulter Counter, the latter was used to quantitate the fragmentation in Flexibacter sp. BH3 and Cytophaga sp. KM57. Both organisms fragmented in the late stationary phase of growth; both shrank rapidly in 0.9% (w/v) saline, and swelled on fixation in 2.5% (v/v) glutaraldehyde. Fixation in 0.025% (v/v) glutaraldehyde gave satisfactory preparations. The glucose concentration of the growth medium had little effect on motility, growth rate or size distribution, whereas an increase in the casamino acid concentration increased the duration of the exponential phase and the yield of cells but inhibited fragmentation and motility.