The Effect Of Metal Ions On Acetone-butanol-ethanol Fermentation

Nowadays the source of oil is gradually exhausted, and pollutions become more and more serious. Bio-butanol is a new potential biofuel, which has attracted wide attention around the world. Bio-butanol is considered to be a highly promising second generation of new biofuels. Butanol is considered as the potential energy to replace gasoline, which is superior to ethanol because of its higher energy density, lower volatility and the ability of gasoline transportation.However, in traditional acetone-butanol-ethanol (ABE) fermentation, butanol’s production and productivity is low with a large amount of byproducts. These factors weaken the competitiveness of microbial butanol fermentation. Hence, the effective way to solve the bottleneck problem is to improve the productivity of butanol fermentation and reduce the amount of byproducts.Lots of previous researches illustrated that the great regulatory effects of mental ions on ABE fermentation. In order to solve the aforementioned problems, the research here used response surface method to optimize the constitution of metal ions in ABE fermentation. The results showed that under the supplementation of 0.0026 g/L ZnSO4·7H2O54.04 g/L CaCO3 and 0.84 g/L MnSO4·H2O, the production of butanol increased from 11.91 g/L to 13.93 g/L, which increased 16.9% compared with the control group.In addition, the research here used batch fermentation method to research the effect of metal ions on ABE fermentation. At the end of fermentation glucose was nearly consumed out, and the production of butanol and total solvent increased to 14.97 g/L and 24.50 g/L, which increased by 28.1% and 27.7% compared with the control group, respectively. The corresponding productivity of butanol and total solvents respectively improved to 0.37 g/L/h and 0.61 g/L/h, which increased by 105.6% and 103.3% compared with the control group, respectively. The ABE fermentation efficiency was effectively improved.We also found the production of butyrate was significantly decreased at the end of fermentation. Then we added butyrate to the control and optimal condition. The results showed when optimal condition fermentation under 1.9 g/L butyrate supplementation, the Max ODe20 increased to 3.66, which increased 14.7% compared with no supplementation. The production of butanol and total solvents increased to 15.12 g/L and 24.86 g/L, while the production of the none supplementation group increased slightly. The synergic effect of Zn2+ Ca2+ and Mn2+ can improve the ability of acid re-assimilation, which re-assimilates more organic acid under high concentration butyrate supplementation.Furthermore, after extraction and analysis of 13 key intracellular metabolites during the fermentation, we discovered that the synergic effects of Zn2+, Ca2+ and Mn2+ can improve the ability of glycolysis process, the enzyme activities of butanol formation process, energy state and reducing equivalents.To sum up, this article studied the effect of metal ions on ABE fermentation. Under optimal condition, fermentation efficiency was significantly improved, which provide important references in the ABE fermentation.