Pigment production in chemostat cultures of Streptococcus bovis - III. Cell clumping and pigment distribution during nonsteady state growth

Streptococcus bovis 2B formed bright red cell clumps in glucose-limited defined medium under certain nonsteady state growth conditions. Scanning electron micrographs showed that clumped cells were more rounded than those from complex medium. Clumped cells appeared to be bound to one another at the cell surface and there was no sign of a polysaccharide matrix. Freeze fractured cells showed that the inner membrane particle distribution was different in the clumped cells from fast growing cells in complex or defined medium. Clumping is potentially a mechanism to decrease transport by reducing the cell surface area. It appears to be a nonsteady state phenomenon, occurring in situations leading to unbalanced growth.