Enhancement of acetic acid tolerance performance in Saccharomyces cerevisiae using histone H3K9 mimicking acetylation
With the increasingly severe energy problem,the design idea of converting lignocellulose,which is abundant renewable resources in nature,into second-generation fuel ethanol provides a way to solve the current energy crisis,food crisis and environmental crisis.However,microorganisms also face a number of technical problems in the process of fermentation to produce second-generation ethanol.Among them,a variety of small molecule chemicals produced by lignocellulosic degradation will not only inhibit the growth and reproduction of microorganisms,but also reduce the fermentation efficiency of microorganisms.Acetic acid is one of the main inhibitors commonly found in many degradation products of lignocellulosic materials.In order to improve the efficiency of microbial lignocellulosic ethanol fermentation,this study selected Saccharomyces cerevisiae,an ethanol fermentation strain with the greatest potential in industrial production,as the model organism,and simulated the acetylation of histone H3K9 by mutating the ninth lysine(K)of histone H3 into glutamine(Q)to investigate the tolerance of histone H3K9Q point mutants to acetic acid,a fermentation inhibitor.The results showed that H3K9Q point mutation could significantly improve the growth performance of Saccharomyces cerevisiae under acetic acid.The growth curve experiment further showed that H3K9Q point mutation could make the strain rapidly enter the exponential phase under 3.5 g/L acetic acid stress,which was shortened from 36 h to 24 h.Moreover,after 48 h of growth in medium with acetic acid,the OD600 of H3K9Q point mutant was about 1.9 times that of the control strain.These results indicated that H3K9Q point mutation significantly improved the acetic acid resistance of Saccharomyces cerevisiae,and this study provided a useful reference for strain optimization in cellulosic ethanol production.
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