Use of elephant grass (Pennisetum purpureum) as substrate for cellulase and xylanase production in solid-state cultivation by Penicillium echinulatum

Abstract The high cost of the enzymes used for the hydrolysis of lignocellulosic biomass is one of the bottlenecks in the production of second-generation ethanol and the use of local biomass, such elephant grass, can help to reduce this cost. In this investigation elephant grass biomass was evaluated as a carbon and inducer source of production of cellulases and xylanases by the fungus Penicillium echinulatum strain 9A02S1 in solid-state cultivation. The highest filter paper activity (13.26 U.g-1 dry matter) and β-glucosidase activity (138.34 U.g-1 dry matter) were obtained on the fifth day of cultivation, in medium containing biomass pre-treated with sulfuric acid and untreated, respectively. The highest endoglucanase activity was 158.44 U.g-1 dry matter in the presence of elephant grass pre-treated with sulfuric acid. The xylanase activity was highest with medium that was formulated with 75% untreated elephant grass and 25% wheat bran (372.62 U.g-1 dry matter). In conclusion, the results showed that it is possible to obtain large amounts of cellulases and xylanases using a cosmopolitan and very low cost substrate such as elephant grass.

摘要 用于木质纤维素生物质水解的酶制剂成本高昂，是第二代乙醇生产的瓶颈之一；利用象草等本土生物质则可有效降低该成本。本研究以象草生物质作为碳源与诱导源，评估其在棘孢青霉（*Penicillium echinulatum*）菌株9A02S1固态培养（solid-state cultivation）产纤维素酶（cellulases）与木聚糖酶（xylanases）中的应用效果。培养第5天时，分别在经硫酸预处理的生物质培养基与未处理生物质培养基中，获得了最高的滤纸纤维素酶活（13.26 U·g⁻¹干物质）与β-葡萄糖苷酶活性（138.34 U·g⁻¹干物质）。在使用经硫酸预处理的象草为底物时，测得最高内切葡聚糖酶活性为158.44 U·g⁻¹干物质。当培养基配方为75%未处理象草与25%麦麸时，木聚糖酶活性达到峰值，为372.62 U·g⁻¹干物质。综上，研究结果表明，利用象草这类分布广泛且成本极低的底物，即可获取大量纤维素酶与木聚糖酶。