Increased Rate of Sorbitol Metabolism Negatively Affects Methanol-Induced Synthesis of Recombinant Enzymes in the Yeast Komagataella kurtzmanii and Komagataella phaffii

It is known that sorbitol metabolism in the yeast K. kurtzmanii and K. phaffii is limited by the level of sorbitol dehydrogenase expression. In the present work, we obtained transformants of K. kurtzmanii and K. phaffii that synthesized the thermostable endoglucanase Egh12 of Thielavia terrestris, xyloglucanase Xgh12b of Aspergillus cervinus, and cathepsin-L CathL of Tribolium castaneum under the control of the methanol-inducible promoter PAOX1 and had different rates of sorbitol metabolism due to additional expression of the sorbitol dehydrogenase gene. Synthesis and secretion of the target enzymes were investigated on media containing methanol and sorbitol in different ratios. The results obtained showed that an increase in the rate of sorbitol metabolism in the producers had a negative effect on the synthesis of target proteins up to complete inhibition of their production. At the same time, low-efficiency sorbitol assimilation by these strains, limited by the expression of sorbitol dehydrogenase or by the concentration of sorbitol in the medium, promoted an increase in the secretion of Egh12 and increased enzyme production up to 30% by stimulating the growth of the cell biomass.