里氏木霉液体发酵选择性合成果胶酶

在摇瓶液体发酵的条件下研究了碳源、氮源、酵母汁和营养盐等因素对里氏木霉选择性合成果胶酶的影响规律,并测定了酶学性质。结果表明:从经济角度考虑宜选用脱汁橘皮粉制备果胶酶;在Mandels营养盐中添加1.0 g/L蛋白胨适合于里氏木霉产果胶酶;以25 g/L脱汁橘皮粉液体发酵48 h,果胶酶活力最高值达到32.6μmol/(min.mL),其中纤维素酶和木聚糖酶的活力被分别控制在0.18、0.63μmol/(min.mL)。该果胶酶的最适pH为6.0,最适温度为50℃,以16μmol/(min.g)的果胶酶振荡水解10 g/L商品果胶粉50 h,酶解得率达80.3%。高效液相离子色谱的分析结果显示果胶酶的主要水解产物为单体半乳糖醛酸,含量达总水解产物的82.5%以上。

Selective synthesis of pectinase from Trichoderma reesei through liquid fermentation

Effects of carbon sources,nitrogen sources,the loading of yeast extract and nutrient salt on pectinase synthesis from Trichoderma reesei Rut C-30 were studied under liquid shake-flask fermentation conditions,and the enzymatic properties were also tested.The results showed that the boiled orange peel(BOP) was selected as the optimum carbon source for pectinase synthesis based on techno-economic analysis,in which only pectinase was selectively synthesized and secreted,but barely cellulase and trace xylanase came together.Adding 1.0 g/L peptone to Mandels salt was suitable nutrient medium for its pectinase synthesis.After culture for 48 h in the medium containing 12.5 g/L BOP,T.reesei produced the maximum pectinase activity of 32.6 μmol/(min·mL),while the cellulase activity and xylanase activity were restricted within narrow limits of 0.18,0.63 μmol/(min·mL),respectively,which reached the higher level according to data.The optimum pH value and temperature were 6.0 and 50 ℃,respectively,under this conditions the enzymatic hydrolysis yield reached 80.3 % after 50 h in 10 g/L commodity pectin solution at pectinase loading of 16 μmol/(min·g).According to detection with high performance anion exchange chromatography,in this enzymatic hydrolysate the main end product was monomers other than oligomers of galacturonic acid,and 82.5 % of pectin was converted into mono-galacouronic acid.