Abstract

Optimization of cellulase production by Bacillus subtilis subsp. subtilis JJBS300 resulted in maximum cellulase (CMCase 9.7 U/g substrate) using wheat bran and rice straw in 1:1 ratio at substrate to moisture ratio of 1:3 at 35 °C and pH 4.0 after 48 h. Partially purified cellulase of B. subtilis subsp. subtilis showed optimal activity at 50 °C and pH 5.0. Among the metal ions, Na⁺, Ca²⁺ and Fe²⁺ stimulated the cellulase activity. Glutaraldehyde and 1-butanol also enhanced the cellulase activity as compared to other solvents. Bacterial cellulase hydrolyzed ammonia-pretreated rice straw more efficiently as compared to sodium-carbonate pretreated and untreated biomass. Optimization of saccharification of untreated and pretreated (sodium carbonate and ammonia) rice straw by bacterial cellulase resulted in high liberation of reducing sugars with enzyme dose of 100 U/g substrate (221 mg/g substrate) at pH 5.0 (103 mg/g substrate) and 50 °C (142 mg/g substrate) after 6 h in ammonia-pretreated rice straw. Furthermore, liberation of reducing sugars increased with incubation time showing maximum reducing sugars (171 mg/g substrate) after 24 h in ammonia-pretreated rice straw. HPLC analysis of enzymatic hydrolysate of ammonia-pretreated rice straw verified the ability of bacterial cellulase in liberation of various monomeric and oligomeric sugars.

摘要

枯草芽孢杆菌亚种纤维素酶生产的优化。枯草芽孢杆菌JJBS300 在 35 °C 和 pH 4.0 条件下，以 1:1 的比例使用麦麸和稻草，在 35°C 和 pH 4.0 条件下，以 1:1 的比例产生最大的纤维素酶（CMCase 9.7 U/g 底物）。部分纯化的B. subtilis subsp.纤维素酶。枯草芽孢杆菌在 50 °C 和 pH 5.0 下显示出最佳活性。金属离子中，Na ⁺、Ca ²⁺和Fe ²⁺刺激纤维素酶活性。与其他溶剂相比，戊二醛和 1-丁醇也增强了纤维素酶活性。与碳酸钠预处理和未处理的生物质相比，细菌纤维素酶更有效地水解氨预处理的稻草。细菌纤维素酶对未处理和预处理（碳酸钠和氨）稻草的糖化优化导致还原糖的大量释放，酶剂量为 100 U/g 底物（221 mg/g 底物），pH 5.0（103 mg/g 底物） ) 和 50 °C (142 mg/g 底物) 在氨预处理的稻草中 6 小时后。此外，在氨预处理的稻草中，24 小时后，还原糖的释放随着孵育时间的增加而增加，显示出最大的还原糖（171 毫克/克底物）。