| This paper studied the technological process of fermenting cellulose to fuel ethanol by saccharomyces cercvisiae YT318 which was obtained through UV mutation. Comparing to original Saccharotnycete YT18, YT318 increased in ethanol production capacity by 15% and decreased in fermentation with 12h. The optimized conditions of preparing cellulose with vapour-exploding was: pressure at 1.2 Mpa, time 5 min, productivity 67.72%.Systematic research on later part of alcohol fermentation and nutrient factors was conducted. It found that YT318 had great capability of alcohol-production on glucose and xylose. Excessive glucose density, toxious material, temperature, acid and so on could inhibit fermentation. Some factors took effect in earlier part of fermentation, while others in latter part. But the synergetic effects of these factors inhibited fermentation even more.Earlier part of fermentation were inhibited at 10% total sugar concentration. Low substrate density was beneficial to improvement of ethanol output. Utilization ratio on raw material could increase from 82.62% to 88.51% in fed-batch fermentation. So it showed substrate inhibition in earlier part of fermentation took more effect that alcohol toxicity in latter part of fermentation.Adding of nitrogen source helped produce alcohol and would shorten fermentation period. Area was the best inorganic nitrogen source which should maintain at high concentration at earlier part of fermentation because of saccharomycete's feature.Oxygen was beneficial to cell growth and living factors production. It would enhance the fermentation if fixed amount of oxygen was maintained.As the best saccharomycete to prepared corn stalk, YT318 had a suitable cultureconditions: temperature 35℃, flaker speed l00r/min, pH 5.5. Ethanol concentration reached 5.5 V/V after 60 h's fermentation and residual sugar was under 0.7%. This demonstrated that it was feasible to produce alcohol in fermentation on cellulose with YT318. |
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