| With the increasing growth of energy crisis and the worsening of environmental problems, the effects of climate changes have become the forefront and crux issues in the energy value chain, which prompts human beings to seek cheap, clean and renewable energy instead of fossil fuel. Thus, the rapid development of bio-fuel has become a priority at present. Fiber fuel butanol is a promising type of new biological energy, which, compared to fuel ethanol, has obvious advantages in the fuel performance and economic performance. There are abundant and cheap cellulosic materials in China. To ferment the materials to produce fuel butanol is becoming a worldwide research hotspot.After low-temperature plasma and nitrosoguanidine (NTG) were used in the composite mutagenesis test on the butanol fermentation strains of Bacillus C2, many mutant strains which can significantly enhance butanol production were obtained in the processes of the flat separation, continuously passaging, liquid fermentation screening,. After the corn mash with the concentration of 7% were fermented by the mutant strains numbered 213, 42 and 414, the amount of butanol and general solvents were enhanced to 12.59, 12.44,12.74 g/L and 20.36,20.14,20.79 g/L respectively, which increased 23.1%, 21.6%, 24.5% and 16.7%, 15.4% , 19.1% respectively compared with the original strains C2.From the physiological and biochemical experiments of the mutant strains, it can be concluded that the mutant strains 42 can react to fluorescent pigment and xylan could be used while the mutant strains 415 could reduce the ability of utilizing cellobiose.After the fermentation conditions of strains 414 were improved, in the 100mL flask fermentation system, the optimum fermentation conditions of the strains were: 100mL liquid, seeds of 24h age, inoculum amount of 10%, pH value of 7 (natural), statically fermented 72h at 37℃. On this condition, using strains of 414 to ferment corn mash of 7%, the amount of butanol and general solvents reached at 12.58 ~ 13.77g / L and 21.25 ~ 22.27g / L respectively. It can be indicated from the butanol fermentation experiments on different concentrations corn straw hydrolysate by the mutations strains that the muton 42 could make the corn straw hydrolysate of 2% and 3% produce 4.10g/L and 3.32g/L general solvents, which increased by 12.94℅, 4.59℅ and 86.52℅, 33.87℅ compared with original strains C2 (3.63g/L and 1.78g/L) and control strains (3.92g/L and 2.48g/L).The butanol fermentation experiments on the mixed sugar and corn straw hydrolysate shows that the toxins in the corn straw hydrolysate could seriously inhibit the growth of microorganism and the fermentation of butanol.In the detoxification experiments on corn straw hydrolysate, the mutant strains 42 could make the amounts of butanol and general solvents rise from 1.39g/L and 2.25g/L to 2.91g/L and 4.62g/L, that is, the amounts increased by 109.35%、105.33% after sodium hydroxide was added to make pH value reach at 7. However, the mutant strains 42 could make the amounts of butanol and general solvents rise from 1.10g/L and 2.18g/L to 3.03g/L and 4.63g/L , that is, the amounts increased by 109.35% and 105.33% after hydrated lime was added to make pH value reach at 7. This means that the detoxification of sodium hydroxide and hydrated lime is not effective. After the 1000 mg/L butanol was added in the corn straw hydrolysate, the amounts of butanol and general solvents increased from 1.74g/L and 2.74g/L obtained in the control experiments to 2.72g/L and 4.34g/L, which raised 56.32% and 58.39%. When 75g / L activated carbon was added, the amount of butanol and general solvents were increased by 36.78% and 29.93% respectively, from 1.74g / L and 2.74g / L to 2.38g / L and 3.56g / L. Compared with the previous experiments, the detoxification of activated carbon is effective. |
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