Heterologous Expression and Characterization of a Ferulic Acid Esterase from Aspergillus aculeatus with Potential Use in Sunflower Seed Processing

Hydrolytic activity for chlorogenic acid (CGA) has been recognized as an important side activity of some types of ferulic acid esterases. The purpose of this work was to enhance the efficient expression of ferulic acid esterase (FAE) and to explore its application in the processing of sunflower seed. Two novel FAEs from Aspergillus aculeatus (AaSD14) were expressed in genetically engineered E. coli BL21 (DE3), and their properties, including temperature, pH, metal ions and substrate specificity, were characterized after purification. Competitive CGA hydrolysis activity was observed in these recombined ferulic acid esterases (reFAEs) with reFAE1 of 246.37 U/g and reFAE2 of 340.95 U/g, which were 56.6 and 78.4 times higher than that of the wild strain (4.35 U/g), respectively. Meanwhile, the fermentation cycle was greatly shortened to 2.0 d. These reFAEs were recognized as type C FAE through substrate specificity assays. Treatment of sunflower seed protein (SSP) using reFAE2 resulted in a remarkable color change, from green to milk-white, confirming the activity of CGA biodegradation. Therefore, it shows certain potential in the processing of sunflower seed and other related foodstuffs.