Effect of acetic acid on ethanol fermentation by engineered Escherichia coli SZ470

Hydrolysis of the aquatic vegetables waste would lead to the generation of some toxic components and by-products, such as weak acids, aldehydes and phenols. The toxic effect of acetic acid on ethanol fermentation by ethanologenic Escherichia colt SZ470 was investigated. The growth curve of Escherichia colt SZ470, specific growth rate (mu), the ethanol yield and consumption of glucose were compared among different concentrations of acetic acid addition in the fermentation medium. Specific growth rate increased as acetic acid concentration lower than 0.6 g/L, but decreased as acetic acid concentrations exceeded 0.6 g/L. When concentration of acetic acid exceeded 0.8 g/L, the exponential groWth phase of Escherichia colt SZ470 expanded from 10 h to above 12 h, moreover, the ethanol yield and consumption of glucose drastically decreased. This result indicates that minor amounts of acetic acid might be helpful with the growth of Escherichia coli SZ470.