Sharma Shivani, Sharma Vinay, Kuila Arindam
Bioscience and Biotechnology Department, Banasthali University, Banasthali, 304022, Rajasthan, India.
3 Biotech. 2016 Dec;6(2):139. doi: 10.1007/s13205-016-0465-z. Epub 2016 Jun 21.
Lignocellulosic bioethanol is an important renewable fuel for transportation purpose. Commercial production of lignocellulosic bioethanol mainly depends on cost of cellulase production, efficient pretreatment and enzymatic hydrolysis process. In the present study cellulase production from Aspergillus niger under submerged fermentation (SmF) was optimized using coconut water as natural medium. Maximum cellulase production (0.53 IU/mL) was achieved within 3 days of incubation using 8 % (w/v) waste paper and 0.07 % (w/v) glucose. The produced cellulase was applied for enzymatic hydrolysis of thermo chemically (dilute acid and alkaline) pretreated biomass (equal mixture of wheat straw and cotton stalk). Optimization of dilute acid and dilute alkaline pretreatment showed dilute alkaline pretreatment was more effective for higher reducing sugar production. Maximum reducing sugar yield of 398.0 mg/g dry biomass was obtained from dilute alkaline pretreated biomass (using 0.5 M sodium hydroxide, 8 % substrate concentration, 120 °C temperature and 20 min of incubation time). The presence of difference sugars (glucose, xylose, mannose, maltose) in the saccharified sample was confirmed by thin layer chromatographic analysis. The effectiveness of dilute alkaline pretreatment was further confirmed by biochemical composition (cellulose, hemicelluloses and lignin) and structural (furrier transformed infrared spectroscopic and scanning electron microscopic) analysis. The above result can be useful for commercial production of lignocellulosic bioethanol.
木质纤维素生物乙醇是一种重要的用于交通运输的可再生燃料。木质纤维素生物乙醇的商业化生产主要取决于纤维素酶的生产成本、高效的预处理和酶水解过程。在本研究中，以椰子水为天然培养基，对黑曲霉在深层发酵（SmF）条件下生产纤维素酶进行了优化。使用8%（w/v）的废纸和0.07%（w/v）的葡萄糖，在培养3天内实现了最大纤维素酶产量（0.53 IU/mL）。将所生产的纤维素酶应用于热化学（稀酸和稀碱）预处理生物质（小麦秸秆和棉秆的等量混合物）的酶水解。稀酸和稀碱预处理的优化表明，稀碱预处理对提高还原糖产量更有效。从稀碱预处理生物质（使用0.5 M氢氧化钠、8%底物浓度、120°C温度和20分钟培养时间）中获得的最大还原糖产量为398.0 mg/g干生物质。通过薄层色谱分析证实了糖化样品中存在不同的糖（葡萄糖、木糖、甘露糖、麦芽糖）。通过生化组成（纤维素、半纤维素和木质素）和结构（傅里叶变换红外光谱和扫描电子显微镜）分析进一步证实了稀碱预处理的有效性。上述结果可用于木质纤维素生物乙醇的商业化生产。
