Abstract:Foaming is a common problem during fermentation. Inhibiting foaming is of great significance for simplifying operation and reducing fermentation cost. Yarrowia lipolytica is a commonly used starting yeast in synthetic biology and for the synthesis of erythritol and other functional sugar alcohols. However, massive foam is produced in the fermentation for the production of erythritol, which needs to be eliminated by defoamers. [Objective] To develop a Y. lipolytica strain with significantly reduced foaming ability, so as to reduce the addition of defoamer in erythritol production. [Methods] According to the principle that non-homologous end joining (NHEJ) is dominant in Y. lipolytica genome recombination, we randomly inserted an artificial DNA fragment into the genome to produce the mutants with reduced or no foaming ability in the fermentation for erythritol production. [Results] After screening, we obtained a mutant without foaming during the fermentation in flask, 50 L pilot reactor, and industrial 75 m3 fermentor. [Conclusion] This mutant obtained can efficiently synthesize erythritol from high-concentration glucose as does the parental strain while producing less foam. The method to obtain defoaming mutant can provide valuable reference for the engineering of other microorganisms.
