Adapting Komagataella phaffii Cultivation Media to REACH Regulations

REACH stands for "Registration, Evaluation, Authorization, and Restriction of Chemicals" and classifies certain substances as harmful to human health and the environment. Boric acid and cobalt dichloride, commonly used as boron (B) and cobalt (Co) sources in cultivation media for Komagataella phaffii, represent such harmful substances. However, B and Co support cellular growth, and yeast harbors a large number of co-containing enzymes. Even though cell physiology (up to 90 g/L) was not affected by the removal of boric acid and cobalt dichloride from the media, recombinant protein production varied when excluding these components from the cultivation media to comply with REACH regulations. Here, we describe how to analyze and potentially adapt a defined cultivation medium for K. phaffii bioreactor cultivations concerning current REACH regulations.