Succinic Acid Fermentation by Escherichia coli Based on Calcium Hydroxide as Neutralizing Agent
Calcium hydroxide is often used as neutralizing agent in the fermentation of organic acids due to its relatively low price and mature matched organic acid separation and purification process.However,in the fermentation of succinic acid,there is a problem of low fermentation yield due to its inability to provide the necessary carbon dioxide for succinic acid synthesis.In this paper,with calcium hydroxide as the neutralizing agent,combined with carbon dioxide pulse feed fermentation,a method for producing succinic acid is established and optimized.When no neutralizing agent is added in the initial stage of fermentation to naturally lower the pH value to 5.7,23％calcium hydroxide solution is immediately added to raise the pH value to 7.5.Then stop adding neutralizing agent,0.2 m3/(m3·min)carbon dioxide gas is introduced until the pH value drops to 6.5,and stop ventilation to make the fermentation broth naturally ferment.When the pH value drops to 5.7,repeat the above operation.Using this method,the fermentation yield,sugar acid conversion rate,average production intensity are 88.47 g/L,96.03％and 2.21 g/(L·h)respectively.The sugar acid conversion rate increases by 298％and 95％respectively compared to using calcium hydroxide as neutralizing agent,without adding or continuously introducing carbon dioxide.This method has provided a new approach to solve the problem of low yield of succinic acid fermentation using calcium hydroxide as neutralizing agent,and also laid a good foundation for the large-scale production of succinic acid using existing organic acid separation equipment.
万方数据
维普
