Abstract

In the present study, the production of cellulase by Trichoderma reesei under solid-state fermentation of nettle biomass was promoted through supplementation of the culture media using carbonaceous additives and comprehensive optimization of the cultivation via the Taguchi method. CMCase activities about 5.5–6.1 U/gds were obtained by fermentation of the autoclave-pretreated biomass, among various chemical and physical pretreatments. Then, several additives including Tween 80, betaine, carboxymethyl cellulose, and lactose were individually or in combination added to the culture media to induce the enzyme production. The results proved that such additives could act as either inducers or inhibitors. Furthermore, CMCase activity surprisingly increased to 14.0 U/gds by supplementing the fermentation medium with the optimal mixture of additives including 0.08 mg/gds Tween 80, 0.4 mg/gds betaine, and 0.2 mg/gds carboxymethyl cellulose. Factor screening according to Plackett–Burman design confirmed that the levels of Urea and MgSO₄ among basal medium constituents as well as pH of the medium were significantly affected CMCase production. By optimizing the levels of these factors, CMCase activity of 18.8 U/gds was obtained, which was noticeably higher than that of fermentation of the raw nettle. The applied procedure can be promisingly used to convert the nettle biomass into valuable products.

摘要

在本研究中，里氏木霉生产纤维素酶通过添加含碳添加剂的培养基和田口法综合优化培养，促进荨麻生物质的固态发酵。CMCase 活性约为 5.5-6.1 U/gds 通过高压釜预处理的生物质的发酵，在各种化学和物理预处理中。然后，将包括吐温 80、甜菜碱、羧甲基纤维素和乳糖在内的几种添加剂单独或组合添加到培养基中以诱导酶的产生。结果证明，这些添加剂既可以作为诱导剂，也可以作为抑制剂。此外，通过向发酵培养基补充添加剂的最佳混合物，包括 0.08 mg/gds Tween 80、0.4 mg/gds 甜菜碱和 0，CMCase 活性令人惊讶地增加到 14.0 U/gds。2 mg/gds 羧甲基纤维素。根据 Plackett-Burman 设计的因子筛选证实了尿素和 MgSO 的水平基础培养基成分中的_{4和培养基的 pH 值显着影响 CMCase 的产生。}通过优化这些因素的水平，获得了18.8 U/gds的CMCase活性，明显高于生荨麻发酵的CMCase活性。该应用程序可有望用于将荨麻生物质转化为有价值的产品。