Study On Endogenous Lycopene Improving Acetic Acid Tolerance In Saccharomyces Cerevisiae

Lignocellulosic pretreatment can produce acetic acid,which is a one of the significant questions in inhibiting lignocellulosic ethanol production.Acetic acid can induce reactive oxidative species(ROS)accumulated in cells,which has a damage to biological macromolecules,leading to changes in protein properties,and even leading to programmed cell death.Therefore,it is one of important challenges to strengthen acetic acid tolerance of strains in the lignocellulosic ethanol industry.In this study,the oxidative stress of acetic acid on cells was analyzed from ROS level.Lycopene is famous as an antioxidant.Therefore,we designed that using lycopene to reduce intracellular ROS in order to improve tolerance to acetic acid tolerance in Saccharomyces cerevisiae.In lycopene-expressing strains,the genes expression levels of oxidative stress sensitive genes,INO1 and CTT1,were lower than that of control,confirming that lycopene can reduce oxidative stress reaction in genes.By constructing a series of lycopene-producing strains,it was proved that the intracellular lycopene yield for the improvement of acetic acid tolerance was 1.475 mg/g DCW.In the fermentation group with an initial glucose concentration of 100 g/L and an acetic acid concentration of 5.5 g/L,The growth lag phase of the strain was shorter than the control strain for 24 h;the glucose consumption rate and the ethanol yield were 2.18 g/(L·h)and 46.41 g/L,respectively,which were 2.13-and 1.84-fold of the control strain.In this study,we first illustrate that the intercellular ROS is associated with acetic acid stress in yeast.This work has improved a new strategy for the development of resistant strains.