Transcriptional Profiling Reveals Adaptive Response and Tolerance to Lactic Acid Stress in Pichia kudriavzevii

Pichia kudriavzevii plays an important role in fermented foods and beverages. In the long domestication process of traditional fermentation, the mechanism of response to lactic acid, a common metabolite and growth inhibitor, is currently unclear in P. kudriavzevii. In this study, the tolerance to lactic acid of P. kudriavzevii C-16, isolated from fermented grains, was compared with its type strain ATCC 24210. Under lactic acid stress, P. kudriavzevii C-16 showed increased biomass yields and lactic acid consumption rates. Then, mRNA sequencing was used to analyze the response to lactic acid in P. kudriavzevii C-16. Results showed that 92 and 96 genes were significantly upregulated, 52 and 58 genes were significantly downregulated, respectively, in P. kudriavzevii C-16 cultured for 12 h and 24 h. The genes, which involved in pyruvate metabolic pathway, ABC transporter proteins, glutamate metabolic pathway, and the biosynthetic pathway of leucine and valine, were observed to be differentially expressed between the P. kudriavzevii C-16 and its type strain ATCC 24210. By analyzing the production of higher alcohols, the concentrations of isobutyl alcohol and isoamyl alcohol produced by P. kudriavzevii C-16 increased significantly. It was consistent with the up-regulation of genes that biosynthesized related amino acids.

Automated summary

This study analyzed the tolerance and gene response of Pichia kudriavzevii under lactic acid stress. It was found that P. kudriavzevii C-16 showed higher biomass yields and lactic acid consumption rates compared to its type strain under lactic acid stress. mRNA sequencing revealed significant upregulation and downregulation of genes in P. kudriavzevii C-16 under lactic acid stress, with differential expression observed in genes related to pyruvate metabolic pathway, ABC transporter proteins, glutamate metabolic pathway, and the biosynthetic pathway of leucine and valine. Additionally, P. kudriavzevii C-16 produced significantly higher concentrations of isobutyl alcohol and isoamyl alcohol under lactic acid stress.