| Fuel ethanol, which is renewable, fully burning and less pollution, spread in the world as a new alternative energy. Fuel ethanol is produced by microbial fermentation in China. Yeast, which is the key factor in fuel ethanol production, affects the ethanol production, so, screening high-yield strain is very important for ethanol. So far, grain starches, such as wheat and corn starch, are used in fuel ethanol production, however, these methods directly threat to the food security. Sweet potato, which is non-grain crop, large output, large planting area, and high energy, is used as new type of energy crop.The industry of fuel ethanol production in sweet potato has still some critical. For example, low yield of ethanol fermented by strain. Few studies on particular sweet potato for fuel ethanol have been documented. The preliminary try to obtain the particular sweet potato for fuel ethanol was done in the present study though five steps, the fundamental experiments on the screening of original strain from distillers yeast, physiology biochemistry experiments of original strains, breeding high-yield strain by protoplast mutagenesis, the tissue culture about sweet potato varieties, screening fermentation process of sweet potato starch, screening particular sweet potato for fuel ethanol The results showed:1. High-yield strain A4 for fuel ethanol production was successfully screened from distillers yeast. A4 had much more possibility to screen higher-yield strains.2. Anqi thermal resistance alcohol activity yeast (Y1) and the yeast screened from distillers yeast (A4) were used as original strains. The results from the physiology biochemistry experiments showed that the original stains are fit for the latter experiment. Furthermore, growth curves laid the foundation for Y1 and A4 protoplast formation and regeneration conditions. 3. The best formation and regeneration conditions was studied from Y1 and A4 protoplast formation and regeneration conditions, the results which reads as follows: Y1:fungus age was 8h, snail enzyme concentration was 2.5%, enzymolysis time was 2h, and 0.7mol/LKC1 used as osmotic pressure stabilizer. A4:fungus age is 10h, snail enzyme concentration is 1.5%, enzymolysis time is 1.5h, and 0.7mol/LKC1 used as osmotic pressure stabilizer. A4-20 which increase yield 28.7%and have a high genetic stability was screened by UV-mutation of protoplast and three-step screening.4. MS medium was used as the basic cultivating medium. Based on taking the orthogonal design experiments and the techniques of plant tissue culture in the current study, the experiment-system of tissue culture and rapid propagation of 6 different sweet potato varieties were successfully established. The results showed that:the most suitable medium for the rapid propagation of "Xushu22" is MS+0.1 mg/L NAA+0.3 mg/L 6-BA+30 g/L sucrose; the most suitable medium for the rapid propagation of other 5 sweet potato varieties is MS+0.1 mg/L NAA+0.1 mg/L 6-BA+30 g/L sucrose.5. The best fermentation process of sweet potato starch was screened taking the orthogonal design experiments. The optimal fermentation conditions were as follows: the ratio of material to water was 1:3, the dosage of saccharifying enzyme was 300 IU/g, the enzymolysis time was 1h, initial pH was 4.5, fermentation time was 96h, inoculation amount was 5%, fermentation temperature was 30℃, added 1% yeast extract as nitrogen source. The results showed that Xushu22, Wanshu3 and 199031-1 could be used as particular sweet potato for fuel ethanol.The yeast increased the ethanol production was screened by UV-mutation of A4 protoplast. The fermentation material can be sufficiently used by high-yield strain. High-yield stain can reduce material waste and increased ethanol production. The experiment-system of tissue culture and rapid propagation of sweet potato established in the present study can rapidly and largely propagate sweet potato, decease the influences of territories and climate, and abundantly offer sweet potato seedlings for large planting. The screening in the study can due to the production for fuel ethanol using sweet potato. It can increase ethanol production and promote the fuel-ethanol industry development. |
PDF Full Text Request