Implementation of a repeated fed-batch process for the production of chitin-glucan complex by Komagataella pastoris

The yeast Komagataella pastoris was cultivated under different fed-batch strategies for the production of chitin-glucan complex (CGC), a co-polymer of chitin and β-glucan. The tested fed-batch strategies included DO-stat mode, predefined feeding profile and repeated fed-batch operation. Although high cell dry mass and high CGC production were obtained under the tested DO-stat strategy in a 94 h cultivation (159 and 29 g/L, respectively), the overall biomass and CGC productivities were low (41 and 7.4 g/L day, respectively). Cultivation with a predefined profile significantly improved both biomass and CGC volumetric productivity (87 and 10.8 g/L day, respectively). Hence, this strategy was used to implement a repeated fed-batch process comprising 7 consecutive cycles. A daily production of 119-126 g/L of biomass with a CGC content of 11-16 wt% was obtained, thus proving this cultivation strategy is adequate to reach a high CGC productivity that ranged between 11 and 18 g/L day. The process was stable and reproducible in terms of CGC productivity and polymer composition, making it a promising strategy for further process development.