The Breeding Of Yeasts With 2-phenylethanol Tolerance And High Yield

2-phenylethanol is a sweet alcohol.It has the rose flower and applies to the tobacco,food,cosmetics,and other industries.In recent years,the need of natural 2-phenylethanol increases constantly.So the biological transformation production methed of the yeast has the very big potential value.But the high level of 2-phenylethanol ethanol has cell toxic to yeast itself,which inhibits the growth of yeast.This topic obtained eight strains of 2-phenylethanol toleranced strain using laboratory preservation strains of s.cerevisiae CWY132 though uv mutagenesis,LiCl ultraviolet composite mutagenesis,60Co?rays mutagenesis,easy wrong PCR method.Also studied the relationship of yield and tolerance.CWY132-18-17 had the highest tolerance and output of 2-phenylethanol.Its tolerance improved 50%,yield increased by 15.2%than CWY132,the more conversion of L-phenylalanine is up to 103.67%.Ultraviolet mutagenesis is the most commonly used method of breeding,but the rate of mutation is very low.By the screening of ultraviolet mutagenes,I have won 21 strains of high 2-phenylethanol tolerance mutations.This paper,by LiCl ultraviolet composite mutagenesis,increased the mutation rate about 10 times.LiCl ultraviolet composite mutagenesis got three strains mutations,one of these could tolerate 3.3 g/L 2-phenylethanol of solid flat plate.Because the selection efficiency of above methods is relatively very low,the later work is based on the experience,using a 60 Co gamma rays mutation breeding method.Through the method,obtaining 5 strains of 2-phenylethanol tolerability strains of the mutations.Because of easy wrong PCR can change genes in a large extent,using this method to get genetic changes of the big mutants.Easy wrong PCR conditions of this method is the key,for many uncertain factors,eventually only obtained one tolerant strain of 2-phenylethanol.In a conclusion,60 Co gamma rays mutation breeding,which breeding cycle is short,is more appropriate breeding method.