Sun Yi-Xin, Shen Bing-Bing, Han Hui-Ying, Lu Yuan, Zhang Bi-Xian, Gao Yun-Fei, Hu Bao-Zhong, Hu Xiao-Mei
College of Life Science, Northeast Agricultural University Harbin 150030 China
Heilongjiang Academy of Agricultural Sciences Harbin 150086 China.
RSC Adv. 2018 Sep 3;8(54):30957-30965. doi: 10.1039/c8ra05729j. eCollection 2018 Aug 30.
Lignocellulosic biomass as one of the most abundant and renewable resources has great potential for biofuel production. The complete conversion of biomass to biofuel is achieved through the effective pretreatment process and the following enzyme saccharification. Ionic liquids (ILs) are considered as a green solvent for lignocellulose pretreatment. However, ILs exhibit an inhibitory effect on cellulase activity, leading to a subsequent decrease in the efficiency of saccharification. The screening of new potential IL-tolerant cellulases is important. In the current study, a fungal strain with a relatively high cellulase production was isolated and identified as HC6. The culture conditions were optimized using corn stover and peptone as the carbon source and nitrogen source at pH 4.0 and 30 °C with an inoculation size of 2% (v/v) for 8 days. It was found that HC6 exhibited potential salt tolerance with the increase of the enzyme production at a salt concentration of 5.0% (w/v). In addition, high enzyme activities were obtained at pH 4.0-6.0 and 50-65 °C. The crude enzyme from HC6 with good thermal stability was also stable in the presence of salt and ILs. Good yields of reducing sugar were obtained by the crude enzyme from HC6 after the saccharification of corn stover that was pretreated by ILs. HC6 with potentially salt-tolerant and IL-tolerant enzymes has great potential application in the enzymatic saccharification of lignocellulose.
木质纤维素生物质作为最丰富的可再生资源之一，在生物燃料生产方面具有巨大潜力。通过有效的预处理过程和后续的酶糖化作用可实现生物质向生物燃料的完全转化。离子液体（ILs）被认为是用于木质纤维素预处理的绿色溶剂。然而，离子液体对纤维素酶活性具有抑制作用，导致糖化效率随后降低。筛选新的潜在耐离子液体纤维素酶很重要。在当前研究中，分离出一株纤维素酶产量相对较高的真菌菌株，并鉴定为HC6。以玉米秸秆和蛋白胨作为碳源和氮源，在pH 4.0和30℃条件下，接种量为2%（v/v），培养8天，对培养条件进行了优化。结果发现，在盐浓度为5.0%（w/v）时，随着酶产量的增加，HC6表现出潜在的耐盐性。此外，在pH 4.0 - 6.0和50 - 65℃条件下获得了高酶活性。来自HC6的粗酶具有良好的热稳定性，在盐和离子液体存在下也很稳定。用离子液体预处理后的玉米秸秆经HC6粗酶糖化后获得了良好的还原糖产量。具有潜在耐盐和耐离子液体酶的HC6在木质纤维素的酶糖化中具有巨大的潜在应用价值。
