Enhanced production of insect raw-starch-digesting alpha-amylase accompanied by high erythritol synthesis in recombinant Yarrowia lipolytica fed-batch cultures at high-cell-densities

摘要

Recently we reported on raw-starch-digesting ability of alpha-amylase from an insect Sitophilus oryzae (SoAMY) expressed in recombinant Yarrowia lipolytica cells, and demonstrated its usefulness in simultaneous saccharification and fermentation processes with industrial yeasts. In this study we applied fed-batch cultures of Y. lipolytica 4.29 strain reaching high-cell-densities (up to 70 [g(DCW)/L]), to enhance SoAMY production. SoAMY activity in the medium reached the peak value of 22,979.23 +/- 184 [AU/L], at volumetric productivity of 121.58 +/- 1.75 [AU/L/h], and yield of 71.83 +/- 3.08 [AU/ggiy roil, constituting roughly 160-fold improvement, compared to the best previous result. The cultivations were accompanied by high production of erythritol (83.58 [g/L]), at the marginal production of mannitol (5.46 [g/L]). Elementary analyses of media constituents, the enzyme and the yeast biomass gave better insight into carbon and nitrogen fluxes distribution. Due to application of genetic engineering and bioprocess engineering strategies, the insect-derived enzyme can be produced at the quantities competitive to microbial catalysts. (C) 2016 Elsevier Ltd. All rights reserved.