Optimization of nutrient medium and process conditions for cell growth of yeast strain Pichia kluyveri K-1

This study aimed to optimize the growth conditions for yeast strain Pichia kluyveri K-1 to maximize cell growth. The effect of several carbon sources (glucose, fructose, maltose, galactose, and glycerol) and their concentrations on the cell growth of P. kluyveri K-1 was examined using the one-factor-at-a-time method. Additionally, the Plackett-Burman design was used to assess the impact of process conditions (temperature and agitation speed) and components of the medium (yeast extract, ZnSO4·7H2O, riboflavin, biotin, MgSO4·7H2O, KH2PO4, MnCl2·4H2O and CaCl2) on the number of viable cells and biomass yield (response variables). The results of the one-factor-at-a-time and Plackett-Burman design studies revealed that temperature, agitation speed, and glucose concentration were the main factors affecting cell growth. The Box-Behnken design and response surface method were used to evaluate the impact of factors, temperature (20-30 °C), agitation speed (40-200 rpm), and glucose concentration (0.5-5% (w/v)), as well as to optimize the process. Based on the experimental results, the predicted models for both response variables were statistically significant. In both predicted models, the agitation speed and glucose concentration had significant impacts on the response variables. The optimum conditions for maximization of a number of viable cells and biomass yield were 21.9 °C, 184 rpm, and 4.8% (w/v) of glucose. Under these optimal conditions, the predicted values of the number of viable cells and biomass yield were 8.68 log CFU/mL and 58.40 g/L, respectively. Validation of the optimal conditions at the experimental level proved the suitability of the proposed models.