Optimizing secretory expression of recombinant human interferon gamma from Kluyveromyces lactis

Biosimilar/biotherapeutic production is becoming a major area of focus for a big chunk of biotechnology industry. Easy licensing and already approved status for clinical use have given it a boost. In the present study, recombinant human interferon gamma (IFNG) was expressed for the first time in Kluyveromyces lactis expression system and its expression was optimized by varying growth parameters and carbon source concentration with the aim of increasing recombinant protein production level. Human IFNG gene was cloned in the genomic DNA of K. lactis by homologous recombination and under unoptimized conditions in shake flask, IFN protein was secreted in the fermentation medium at a level of 175 mu g/L quantified by ELISA assay. After the optimization of expression conditions using one-variable-at-a-time technique, expression level was enhanced by 2.2-folds. Substrate inhibition studies revealed that up to 80g/L of lactose is well tolerated by K. lactis cells for its growth but more than 80g/L of lactose causes remarkable reduction in biomass production.