[Effect of microorganism population density on protein metabolism]

The influence of population density of yeasts Candida utilis on the protein synthesis was investigated using 14C-L-leucine. After 15--30 minutes of exposure in 14C-L-leucine, the isotope incorporation into the protein was negligible at subcritical density of cell suspension (10(4)--5X10(5) cells/mm3), but then beginning from the 10(6) cells/mm3 density, a sharp activation of incorporation was observed. With increased incubation time up to 60--120 minutes for high density suspension (more than 10(6) cells/mm3), the degradation of newly-synthesized protein is the more the higher the cell concentrations and incubation time. The changes of protein synthesis intensity seem to be not associated with the influence of such traditional factors as nutrient medium exhaustion, toxicosis, change of hydrogen ion concentration and oxygen deficiency. It is suggested that structurally functional shifts in cells initiated by intercellular interactions may underlie the dependence of protein synthesis on the suspension culture density.