Optimization of the heterologous production of a Rhizopus oryzae lipase in Pichia pastoris system using mixed substrates on controlled fed-batch bioprocess.

In this work a systematic study of the influence of methanol set-point and sorbitol feeding rate in fed-batch operation with a Pichia pastoris Mut(s) strain producing Rhizopus oryzae lipase is presented. Different experiments were made at a constant methanol set-point of 0.5, 2 and 4gl(-1), controlled by a predictive algorithm at two different sorbitol feeding rates to assure a constant specific growth rate of 0.01 and 0.02h(-1), by means of a pre-programmed exponential feeding rate strategy. Lipolytic activity, yields, productivity and specific productivity, but also specific growth, consumption and production rates were analyzed showing that the best values were reached when the methanol set-point was 2gl(-1) with a low influence of the constant specific growth rate tested. The sorbitol addition as a co-substrate during the induction phase avoids the severe decrease of the specific production rate obtained when methanol was used as a sole carbon source and it permits to achieve higher ROL production.