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，是制约第二代乙醇生产的瓶颈之一；采用象草等本土生物质则可有效降低该成本。本研究在固态培养条件下，评价了象草生物质作为棘孢青霉（Penicillium echinulatum）9A02S1菌株产纤维素酶与木聚糖酶的碳源及诱导源的应用效果。培养第5天时，分别在经硫酸预处理的象草培养基与未经处理的象草培养基中，获得了最高的滤纸酶活（13.26 U·g⁻¹干物质）与β-葡萄糖苷酶活（138.34 U·g⁻¹干物质）。在添加经硫酸预处理象草的培养基中，内切葡聚糖酶活峰值达158.44 U·g⁻¹干物质。当培养基配方为75%未经处理的象草与25%麦麸时，木聚糖酶活达到最高值372.62 U·g⁻¹干物质。综上，本研究结果表明，利用象草这种分布广泛、成本极低的底物，可高效获取大量纤维素酶与木聚糖酶。