科研之友
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摘要
Xylooligosaccharide (XOS) derived from enzymatic hydrolysis of biopolymers is of considerable importance in food and biotechnological industries. To create added value products from hardwood xylan, xylanase (XynB) and er-glucuronidase (AguA) from Thermotoga maritima were co-produced in Escherichia colt through dual-promoter and bicistronic constructs and evaluated for enzymatic production of XOS using reducing end assay and high-performance liquid chromatography (HPLC) analysis. The highest XynB and AguA yields were obtained with pET-28a-xynB-Hspr-aguA when inducted with IPTG at a concentration of 0.8 mM for 8 h at 42 degrees C for AguA and 37 degrees C for XynB. Cocktail enzymes of AguA and XynB applied on beech xylan materials resulted in significantly different amounts of produced xylose, xylobiose and 4-O-methylglucuronic acid, as well as different XOS profile. Antioxidant activity of XOS mixtures was carried out by three different methods, which are DPPH and hydroxyl radical scavenging activity and total antioxidant capacity assays. Antioxidant activities of XOS mixture generated using XynB and AguA was superior to those generated by XynB, which suggested that the antioxidant capacity related to higher degrees of hydrolysis and XOS profile. The results suggest that the potential of recombinant cocktail enzyme of XynB and AguA for the application in preparing nutritional health oligosaccha rides useful in food and pharmaceutical industries. [GRAPHICS] .
- 出版日期2018
- 单位南京师范大学
