In the above equation, is the desired constant specific growthrate. The following set point values of the constant specific growthrate () were used in different experiments: 0.05, 0.10 and 0.15 h−1.The initial working volume (V0) was 1 L and the final volume was1.5 L. X0was the initial concentration of the biomass and X wasthe biomass concentration at time t. A peristaltic pump (Master-flex model no. 7551-10; www.masterflex.com) was controlled toprovide the necessary feeding rate during the exponential feedingoperation. The feed was palm oil, the carbon source. Nitrogen wassupplied via the ammonia solution that was used for pH control.