Metabolic engineering of the acid-tolerant yeast Pichia kudriavzevii for efficient L-malic acid production at low pH

Soluble pyridine nucleotide transhydrogenase (EcSthA) derived from Escherichia coli was introduced into the L-malic acid producing strain MA009-5 of Pichia kudriavzevii to obtain strain MA009-10. It was found that MA009-10 was superior to MA009-5 in terms of L-malic acid titer, glucose consumption rate, and glucose/L-malic acid conversion rate. To elucidate the effect of EcSthA expression on L-malic acid synthesis, we analyzed the RNA-seq data of both strains. Comparative gene expression profiling of RNA-seq data from strains MA009-5 and MA009-10.