Valorisation of cheese whey as substrate and inducer for recombinant protein production in E. coli HMS174(DE3)

Abstract

Every year worldwide around 190 million tons of cheese whey are generated resulting in a huge environmental burden. We recently published a study where we showed that E. coli strain HMS174(DE3) can be cultivated using only lactose as C-source and inducer. Motivated by the results we investigated using a concentrated whey feed instead of the lactose feed. Spray drying whey and dissolving the powder allowed preparation of a 40-fold concentrated whey containing 91% lactose and 81% protein of the original whey. Cultivations using the concentrated whey feed instead of a defined lactose feed revealed 39% higher growth rates, 24% higher biomass yields and even higher specific product titers for the model enzymes, flavanone 3-hydroxylase and chalcone 3- hydroxylase. Our strategy simultaneously provides a cheap substrate for large-scale production of technical enzymes and an excellent opportunity for cheese whey valorization, reducing the biological burden resulting from whey wastewaters.