UTILIZATION OF AGROINDUSTRIAL BY-PRODUCTS AS SUBSTRATE IN ENDOGLUCANASE PRODUCTION BY Streptomyces diastaticus PA-01 UNDER SUBMERGED FERMENTATION

Abstract Endoglucanase production under submerged fermentation was studied using sugarcane bagasse (SCB) and oat bran (OB) as carbon source and corn steep liquor (CSL) as nitrogen source, in different concentrations using factorial design. Streptomyces diastaticus PA-01, isolated from a soil cave in Brazil, was selected as cellulolytic strain. The results after experimental validation showed that a medium containing 2.4% (w/v) SCB and 1.3% (w/v) CSL led to the highest production, 1,180.3 U.L-1 of endoglucanase, after the 5th-day. A good level of endoglucanase (1,039.3 U.L-1) was obtained after the 4th-day when 2.0% (w/v) OB and 1.65% (w/v) CSL were used. The pH and temperature profiles showed thermoacidophilic endoglucanase activity, with 70% of maximum activity at 50ºC, after 4 hours of pre-incubation. This is the first report on endoglucanase production by S. diastaticus PA-01 in the presence of SCB and OB. The strong positive effects of some metal ions (Zn2+, Mn2+ and Ba2+) on endoglucanase activity when this strain was grown on OB is an interesting biochemical characteristic for future biotechnological applications.

摘要：本研究以甘蔗渣（sugarcane bagasse, SCB）与燕麦麸皮（oat bran, OB）为碳源、玉米浆（corn steep liquor, CSL）为氮源，采用析因设计设置不同浓度梯度，探究了深层发酵条件下内切葡聚糖酶的生产情况。实验选用从巴西土壤洞穴中分离得到的产纤维素酶菌株——淀粉液化链霉菌（Streptomyces diastaticus）PA-01。经实验验证结果显示，当培养基中含有2.4%（w/v）甘蔗渣与1.3%（w/v）玉米浆时，发酵至第5天可获得最高酶活，达1180.3 U·L⁻¹内切葡聚糖酶。当采用2.0%（w/v）燕麦麸皮与1.65%（w/v）玉米浆时，发酵至第4天即可获得较高水平的内切葡聚糖酶活（1039.3 U·L⁻¹）。pH与温度特性分析表明，该酶为嗜热嗜酸型内切葡聚糖酶，经4小时预孵育后在50℃条件下可保留70%的最大酶活。本研究为首次报道淀粉液化链霉菌PA-01以甘蔗渣与燕麦麸皮为底物生产内切葡聚糖酶的研究成果。当该菌株以燕麦麸皮为底物时，Zn²+、Mn²+与Ba²+等金属离子对其内切葡聚糖酶活具有显著正向促进作用，这一优良生化特性为其未来的生物技术应用提供了潜在可能。