Interleukin-1beta production by Zygosaccharomyces bailii [pZ3KlIL-1beta] in aerated fed-batch reactor: importance of inoculum physiology and bioprocess modelling

A cultural system, aimed at the production of human interleukin-1beta (IL-1beta) with cells of a nonconventional yeast transformed for interleukin expression, Zygosaccharomyces bailii [pZ3KlIL-1beta], was realized. Interleukin production was accomplished in a reactor operating in fed-batch mode to avoid sugar overflow metabolism, limitations with respect to oxygen transfer, and achieve high cell density. Batch operation mode was employed only to characterise the producer strain and experimentally estimate kinetic parameters. In parallel with strain characterisation, a mathematical model was developed. The comparison between simulations and experimental data allowed to evidence the importance of physiological state of inoculum, being only a fermentative one suitable to sustain a given exponential growth. The respiratory capacity of Z. bailii [pZ3KlIL-1beta], resulted to be affected by stirring. The theoretical and experimental approach allowed the bioprocess optimisation.