FEMS Microbiol Lett 2019 03;366(5)
Microbial Cell Factory Research Team, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani 12120, Thailand.
In this study, production of fungal phytase in thermotolerant methylotrophic yeast Ogataea thermomethanolica TBRC656 employing methanol-inducible OtAOX promoter and sucrose-inducible OtMal promoter was investigated in a high cell density fed-batch fermentation. Although a similar maximum cell concentration was obtained in both expression systems, the OtMal system gave ~2-fold higher phytase activity, specific yield, production yield, volumetric productivity and specific productivity rate compared with the OtAOX system. In addition to being more efficient, the OtMal system is more flexible because sucrose or sugarcane molasses can be utilized as less expensive carbon sources instead of glycerol in batch and fed-batch stages. Phytase yields from the OtMal system produced using sucrose or sugarcane molasses are comparable with those obtained with glycerol. We estimate the cost of phytase production by the OtMal system using sucrose or sugarcane molasses to be ~85% lower than the OtAOX system.