INFLUENCE OF CO2 VENTILATION ON MICROBIAL CULTIVATION IN SHAKE-FLASKS

The cell yield of Saccharomyces cerevisiae was 20% lower in Erlenmeyer flasks than in the aerated-flask or jar fermenter operated under the same initial volumetric O-2 transfer coefficient (55 h(-1)). This was due to the lower ventilation capacity of the Erlenmeyer flask as refle cted by the changes in the partial pressures of gases in the head spac e. Although there was no significant change in the partial pressures o f gases during the cultivation in the aerated-flask or jar fermenter, a sharp rise in pCO(2) and fall in pO(2) was observed in the Erlenmeye r flask. The degree of ventilation in shake-flasks also affected the r esults of enrichment cultivations of soil samples.