Characterization of Feruloyl Esterase from Klebsiella oxytoca Z28 and Its Application in the Release of Ferulic Acid from De-Starching Wheat Bran

Feruloyl esterase (EC3.1.1.73; FAE) can degrade biomass to release ferulic acid (FA), which has a high application in bioprocessing, food, pharmaceutical, paper, feed, and other industrial fields. A strain of Klebsiella oxytoca Z28 with ferulic esterase activity was screened from Daqu. In addition, the FAE gene was expressed in Escherichia coli BL21 (DE3). The enzyme consists of 340 amino acids with a molecular mass of 37.7 kDa. The FAE enzyme activity was 463 U/L when the substrate was ethyl 4-hydroxy-3-methoxycinnamate and the optimum temperature and pH were 50 degrees C and 8.0, respectively. The enzyme had good stability at temperatures of 25-40 degrees C and a pH of 8.0. Ba2+, Cu2+, Mn2+, and Ca2+ had a strong inhibitory effect on the enzyme activity, and Na+ had a promotive effect on the enzyme activity. The de-starching wheat bran was degraded by KoFAE, and the FA release was up to 227.15 mu g/g. This indicated that the heterologous expression of KoFAE from Klebsiella oxytoca Z28 in E. coli had a certain potential of biodegradation, which can be applied to the degradation of agricultural waste to obtain high value-added FA products.

Automated summary

A strain of Klebsiella oxytoca Z28 with ferulic esterase activity was isolated from Daqu, and the FAE gene was expressed in Escherichia coli BL21 (DE3). The enzyme showed good stability and activity at favorable temperature and pH. KoFAE from Klebsiella oxytoca Z28 has the potential to degrade agricultural waste and produce high value-added ferulic acid products when expressed heterologously in E. coli.