Studies On The Isolation Screening Identification And Optimization Of Yeast Fermenting Xylose For Production Alcohol

The experiment studied on the isolation and screening and identification and optimization of yeast and the improvement of fermentation conditions.1 Study on the isolation and screening and identification of yeastfermentation xylose for production alcoholThis paper with the dilution flat pane method and lineation separation method isolated yeast that ferment xylose for production alcohol from corrupted straw and corrupted corn stalks and corn soil.Then applied the isolated yeast stubs for fermenting different dense xylose to screen yeast.The Screening indicators include Whether produce alcohol and the rate of production alcohol and the level of production alcohol. Acquired 3 stubs yeast can make use of xylose as the unique carbon source to grow and make use of xylose to produce higher level of alcohol.The 3 stubs yeast number is respectively 104 and 108 and 113.Identificated them by different appearance characteristics and different physiological and biochemical reactions. The identification result is that the 3 stubs yeast is Candida utilis.2. Study on the optimization of yeast.The yeast by UV mutagenesis fistly. Then by researching about UV mutagenesis parameters.The conclusions are that suit UV mutagenesis dose is 25w, suit UV mutagenesis time is 8 minute, suit bacilli concentration is 10~8个/mL. The yeast after UV mutagenesis were diverted to xylose fermentation liquor for screening yeast strains.Choosing the yeast with better ability of fermentation xylose for sodium nitrite mutagenesis, UV and sodium nitrite compound mutagenesis.After these mutagenesis. diverted yeast into xylose fermentation liquor for screening out the best yeast strains with the highest xylose conversion rate.3 Study on the optimization of conditions yeast fermenting xylose forproduction alcohol.By choosing suit fermentation time and fermentation speed and fermentation temperature and the rate of shaking bottle fermentation and so on.The conclusions are that the suit fermentation time is 5days , suit fermentation temperature is 25℃, the suit rate of shaking bottle fermentation is 100r/min,suit pH is 5.5, suit nitrogen is ammonia sulfate.Immobilized yeast is better in ferment xylose than not immobilized yeast.4 Study on the methods of improving yeast protoplasm formationrate.By studing on Ultrasonic time, the concentration of snails, temperature of protoplasm formation to choose better method of yeast protoplasm formation rate. The conclusions are that the appropriate method of yeast protoplasm formation rate is Ultrasonic and snails treat yeast at the same time 4h, the concentration of snails2.5%.