Monitoring of sorbitol in Pichia pastoris cultivation applying sequential injection analysis

A simple and robust analyser system based on sequential injection analysis for the determination of sorbitol in Pichia pastoris MutS phenotype batch fermentation is described. Applicability for the bioprocess monitoring of sorbitol in batch culture medium in a concentration range of 8–1.5 g l−1 with satisfying sorbitol recovery was demonstrated during 60 h. Optimization of physical and chemical parameters is further described. The method proved to be reproducible (R.S.D. < 3%), robust, and fast (17 injections per hour). The SIA sorbitol analyzer showed to be applicable for the monitoring of sorbitol concentration in a mixed substrate P. pastoris fermentation strategy. No interference of methanol was observed. The method is suited for the implementation of sorbitol concentration closed-loop control strategies and for the study of the effect of sorbitol concentration in heterologous protein productivity.