Production of citric acid by Candida lipolytica Y1095: Effect of glucose concentration on yield and productivity

The effects of temperature and initial pH on growth of Candida guilliermondii Y 488, Candida lipolytica Y 1095, Yarrowia lipolytica Y 7576, and Saccharomycopsis lipolytica DRL 99 were evaluated. All four yeasts exhibited maximum biomass production at 27°C. Except for S. lipolytica DRL 99, increased agitation nearly doubled the amount of biomass produced at 27°C. The growth of S. lipolytica DRL 99 was also affected by initial medium pH. Based on the results of these experiments, C. lipolytica Y 1095 was selected for citric acid production studies in a 2-1 batch fermentor. At a glucose concentration of 3% w/v, the maximum specific growth rate of C. lipolytica Y 1095 was 0.38 h-1. During the production phase, citric acid yields ranged from 0.50 to 0.79 g citric acid produced per gram glucose consumed and the volumetric productivity ranged from 0.27 to 0.60 g citric acid per liter per hour. Final citric acid concentrations ranged from 13.6 to 78.5 g citric acid per liter and were dependent on the initial glucose concentration in the production medium.