Breeding Of Xylose Fermentation To Produce Ethanol Strains And Optimization Of Fermentation Conditions

Along with the rapid development of the world economy. International crude oil prices have soared, the increasingly serious environmental pollution, oil as a non-renewable resources are also running out. In recent years, oil crisis enormous implications for the world, such as ethanol fuel oil development alternative product problems need to be solved urgently. As a traditional fermentation products and potential fuel, ethanol has been recognized as the most the prospects of development of renewable clean energy, one of fuel ethanol as a kind of renewable clean fuel by the various countries' favor. Makings production of the fuel ethanol called recognized the second generation of fuel ethanol. Cellulose is the most abundant and cheap renewable resource, cellulose as raw material to produce ethanol can be used in saving food and waste treatment and environmental protection that plays a certain role. Hemicelluloses easily be acid or enzyme hydrolysis product, its hydrolysis for percent of 85～90%, after the glucose and xylose was second. Therefore, the development and utilization of xylose fermentation ethanol production has important application value for study. Breeding efficient use of xylose substrate and effectively produce ethanol microorganism strains is the key. This study to produce ethanol laboratory pichia guilliermondii screening based on xylose, yeast strain of microbial fermentation ethanol production and use, mutation breeding, corn straw hydrolysate on directional domestication, in order to improve the ethanol production, for further improved strains lay a foundation of work for using the lignocellulose materials to produce fuel ethanol to realize industrialization production provides experiment basis.From the results:1,Using the laboratory screening obtaining pichia guilliermondii as starting strain, through three rounds of UV and the NTG alternately mutation breeding unselective and determine the best conditions for mutation breeding ultraviolet mutagenesis bacteria optimum dilution concentration for 10-5, best ultraviolet irradiation time for 25s, The NTG mutagenesis bacteria optimum dilution concentration for 10-6, the best mutagenesis NTG mutagenesis 40min, three-wheeled alternate mutagenesis gain time for ethanol production volume is high mutants after strains of C3-10, this mutations ethanol production is the highest 13.2%, than the original bacteria ethanol production increase 8.05%.After several nestin training, it shows good genetic stability, This C3-10 strains for fermentation strains on the following experiment. 2,Through the C3-10 strains Xylose producing for ethanol fermentation, using software Design-Expert with Box-Behnken test and the response surface method optimization fermentation medium and fermentation conditions have the following conclusions:Determine the best fermentation medium formula for:55g D-xylose,5g yeast powder,2.4g KH2PO4,0.3g MgSO4,1 Ldistilled water, ethanol production reaches 14.71%.Determine the best optimization for fermentation conditions:temperature 29℃, starting pH5.6, inoculation quantity 5%, rotate speed 100r/min, ethanol production reaches 15.01%.3,Will corn straw powder and concentration of 4% of dilute sulphuric acid mixing, in pressure steam sterilization is 110℃conditions in dealing with 60min, preparation of corn straw hydrolysis fluid of mutations C3-10 for domestication, obtain growth good strains, ethanol production reaches 16.08%, ethanol production increased domestication before 1.07%.