Production of citric acid, useful as e.g. flavoring in foods and pharmaceuticals, by growing Yarrowia lipolytica that has been modified to increase isocitrate lyase activity

摘要

Production of citric acid (I) in Yarrowia lipolytica by transformation with a vector that contains a sequence (A) encoding isocitrate lyase activity, is new. Production of citric acid (I) in Yarrowia lipolytica comprises first transforming the cells with a vector, capable of multiple genomic integration, that includes an expression cassette having a sequence (A) encoding isocitrate lyase (ICL) activity and including a selection marker gene (SMG). Transformed clones are selected in a suitable nutrient medium for those that have acquired multiple copies of both (A) and SMG, then these are cultured under deficiency conditions, with a carbon source, and (I) purified. Independent claims are also included for: (1) vector for genomic integration, containing at least one sequence that encodes an ICL protein of 540 amino acids, sequence (1) given in the specification; (2) genetically modified strains of Y. lipolytica that contain many copies of (A) integrated stably into its genome; (3) expression cassette that contains many copies of (A); and (4) the protein (1).