OVERPRODUCTION OF RIBOFLAVIN IN YEAST

摘要

Recombinant strains of Bacillus subtilis for the production of riboflavin by fermentation have been described, e.g. in EP 405 370. These strains carry the riboflavin operon under the control of a strong promoter directing the production of the cognate enzymes in large amount. The gene constructs of the riboflavin operon under the control of a strong promoter can be present at one or several different locations on the B. subtilis chromosome. The incorporation of an additional gene of the riboflavin pathway under the control of a strong promoter at a separate locus on the B. subtilis chromosome has also been shown to increase the yield of riboflavin obtained by fermentation, see EP 821 063. Thus the present specification provides a yeast strain which has been transformed by a recombinant DNA sequence comprising a DNA sequence which upon expression in a suitable host cell encodes at least one polypeptide with riboflavin biosynthetic activity and which DNA sequence is transcriptionally linked to a promotor functional in such yeast strain. The yeast strain may belong to the group of flavinogenic yeasts which overproduce riboflavin under conditions of iron starvation. The specification discloses the following groups: Schwanniomyces, preferably Schwanniomyces occidentalis, Debaryomyces, preferably Debaryomyces kloeckeri, Torulopsis, preferably Torulopsis candida, or Candida, preferably Candida guilliermondii or Candida famata.