Transcriptomic and metabonomic to evaluate the effect mechanisms of the growth and aroma-producing of Pichia anomala under ethanol stress

Ethanol stress is an important environmental factor that affects physiological metabolism and aroma-producing capacity of yeast during the brewing process of alcoholic products. To explore the mechanisms of the growth and aroma-producing metabolism of Pichia anomala under ethanol stress, transcriptomic and metabolomic results were collected from different concentrations (3%, 6% and 9%) of the ethanol stressor, and genes, metabolites and metabolic pathways that relate to growth and aroma-producing were screened. Integrated transcriptomic and metabolomic results showed that P. anomala could respond to ethanol stress by activating purine and pyrimidine, glycerophospholipid and antioxidant metabolic pathways. However, the damage to the growth of P. anomala under ethanol stress was closely related to the inhibition of carbohydrate metabolism, ABC transporter, energy metabolism and amino acid pathways, the influence on these pathways became more serious with the increase of ethanol concentrations. Meantime, the decrease in production of phenethyl alcohol and isoamyl alcohol was related to the significantly down-regulated of ARO9, ARO10, ADH1 and ADH2 genes expression in phenylalanine, tyrosine and tryptophan, and glycolysis pathways of P. anomala under ethanol stress. The enhanced expression of ATF1, EAT1, EEB1 and TGL2 genes in P. anomala was the main reason for the high yield of ethyl caproate and ethyl acetate under ethanol stress. These results revealed a theoretical basis for further study of the effect mechanisms of ethanol stress on P. anomala and molecular targets for the construction of genetic engineering strains with high ethanol tolerance and high aroma production.