Lactic acid production by Saccharomyces cerevisiae expressing a Rhizopus oryzae lactate dehydrogenase gene.

摘要: This work demonstrates the first example of a fungal lactate dehydrogenase (LDH) expressed in yeast. A L(+)-LDH gene, ldhA, from filamentous fungus Rhizopus oryzae was modified to be under control Saccharomyces cerevisiae adh1 promoter and terminator then placed 2 micro -containing yeast-replicating plasmid. The resulting construct, pLdhA68X, transformed tested by fermentation analyses haploid diploid yeast containing similar genetic backgrounds. Both recombinant strains utilized 92 g glucose/l approximately 30 h. isolate accumulated 40% more lactic acid with final concentration 38 acid/l yield 0.44 acid/g glucose. optimal pH for production strain 5. LDH activity this remained relatively constant at 1.5 units/mg protein throughout fermentation. majority carbon still diverted ethanol pathway, as indicated yields between 0.25-0.33 g/g S. mutants impaired were pLdhA68X an attempt increase minimizing conversion pyruvate ethanol. Mutants diminished decarboxylase disrupted alcohol did result transformants production. However, efficiency also decreased.