宇佐美曲霉阿魏酸酯酶与木聚糖酶协同作用降解小麦麸皮制备阿魏酸

Synergistic effect of feruloyl esterase and xylanase from Aspergillus usamii in preparation of ferulic acid by degradation of wheat bran

目的利用宇佐美曲霉(Aspergillus usamii)阿魏酸酯酶与木聚糖酶协同降解小麦麸皮,制备阿魏酸(ferulic acid,FA)。方法将工程酵母菌P.pastoris GS115/AusfaeA和GS115/Ausxyn11A经甲醇诱导发酵,分别获得重组阿魏酸酯酶和木聚糖酶。在pH 5.0、40℃、料液比1∶60(g∶ml)、水解10 h的条件下,探讨木聚糖酶添加量、阿魏酸酯酶与木聚糖酶协同作用对阿魏酸酯酶水解去淀粉麦麸(destarched wheat bran,DSWB),释放FA的影响,并检测酶解产物FA的体外抗氧化活性。结果在0.5g DSWB中单独加入56U阿魏酸酯酶时,FA的释放率为碱提等量麸皮总FA含量的19.48%;在此基础上添加木聚糖酶,能促进阿魏酸酯酶进一步释放FA,当木聚糖酶添加量为300 U时,FA的释放率从19.48%上升至70.10%;木聚糖酶单独作用于DSWB未检测到FA的释放;在反应体系中先添加木聚糖酶,能释放1.23 mg FA,比先添加阿魏酸酯酶提高了0.3 mg;随着FA浓度的增加,FA的还原能力及其对DPPH自由基和羟基自由基的清除能力均呈稳定增长,各浓度FA对羟基自由基的清除能力均高于对DPPH自由基的清除能力。结论阿魏酸酯酶与木聚糖酶之间存在协同作用,双酶共同作用,有利于小麦麸皮的降解,提高FA的释放率。

Objective To prepare ferulic acid（FA）by degradation of wheat bran via the synergistic effect of feruloyl esterase and xylanase from Aspergillus usamii（abbreviated as reAusFaeA and reAusXyn11A respectively）. Methods P. pastoris GS115 / AusfaeA and GS115 / Ausxyn11A were fermented under induction of methanol to express reAusFaeA and reAusXyn11A. The effects of reAusXyn11A content and its synergistic mode with reAusFaeA on the lysis of destarched wheat bran（DSWB）and release of FA were investigated at pH 5. 0,40 ℃ and a ratio of solid to liquid of 1 ∶ 60（g ∶ ml） for 10 h,and the antioxidant activity in vitro of FA was determined. Results After 56 U reAusFaeA was added into 0. 5 g DSWB,the release rate of FA was 19. 48% of total FA content extracted with alkaline. However,further addition with reAuXyn11A enhanced the release of FA. After 300 U reAuXyn11A was added,the release rate of FA increased from 19. 48% to 70. 10%. No release of FA was detected in the DSWB treated with reAuXyn11A alone. When reAuXyn11A was added into the reaction system at first,the release of FA was 1. 23 mg,which increased by 0. 3 mg as compared with that when reAusFaeA was added after first. With the increasing FA concentration, the reduction ability of FA as well as its clearance abilities to free DPPH radical and free hydroxide radical increased stably. However, the clearance abilities of FA at various concentrations to free hydroxide radical were stronger than those to free DPPH radical. Conclusion Sig- nificant synergistic interaction between the reAuFaeA and reAuXyn11A was observed,which was beneficial to the degra- dation of wheat bran and enhanced the release of FA.