Optimization of growth conditions of the postharvest biocontrol agent Candida sake CPA-1 in a lab-scale fermenter

AIM: To maximize the growth (expressed as number of viable cells per millilitre) of the postharvest biocontrol agent Candida sake CPA(-1) at laboratory scale conditions. METHODS AND RESULTS: Growth conditons (aeration, agitation speed and inoculum size) were studied in batch conditions in a 5 l fermenter using molasses and urea as growth medium. Consumption of sugars and urea were analysed. Fed-batch studies were also carried out. Glucose and fructose were consumed during the exponential growth phase and were depleted after 18 h of growth. On the contrary, C. sake cells assimilated sucrose during the stationary phase. There was not growth improvement when fed-batch technology was used. Addition of an extra amount of glucose or molasses after 18 h of growth did not contribute to increase final population. CONCLUSIONS: Maximum growth (about 8 x 10(8 )CFU ml(-1)) was obtained at batch fermentation after 30 h growth at 400 rev min(-1), 150 l h(-1) of air and initial concentration of 106 CFU ml(-1). SIGNIFICANCE AND IMPACT OF THE STUDY: The results obtained in this study are an approach for further upscaling of C. sake production.