Abstract

Removal of xylan in plant biomass is believed to increase cellulose hydrolysis by uncovering cellulose surfaces for cellulase adsorption and, in turn, catalysis reaction. Herein, we describe an eco-friendly method by culturing a xylanolytic Bacillus firmus K-1 on rice straw to remove xylan. The bacterium was grown on 2.5% (w/v) rice straw with different biomass particle sizes for two days at 37 °C. We found that the particle sizes ranged from <1 to 5 mm gave a similar xylan removal degree (about 21%). Besides, the porosity and disintegration of the rice straw fibers were observed at the molecular level. The digestibility of pretreated rice straw was tested with different commercial cellulase cocktails. We found that the pretreated rice straw was more susceptible to enzymatic hydrolysis, giving 30–70% glucan conversion than the untreated one. The degree of cellulose hydrolysis depended strongly on the kinds of enzyme and their formulations.

• Highlight

• Culturing B. firmus K-1 on rice straw yielded about 21% removal of xylan.

• Particle sizes (of 1–5 mm) had negligible effects on xylan removal efficiency.

• The degree of glucan conversion in pretreated biomass relied on enzyme formulation.

摘要

据信去除植物生物质中的木聚糖通过暴露纤维素表面以进行纤维素酶吸附并进而催化反应来增加纤维素水解。在此，我们描述了一种生态友好的方法，即在稻草上培养木聚糖分解芽孢杆菌K-1 以去除木聚糖。细菌在 2.5% ( w/v) 不同生物质颗粒大小的稻草在 37 °C 下放置两天。我们发现粒径范围从 <1 到 5 毫米给出了相似的木聚糖去除程度（约 21%）。此外，在分子水平上观察到稻草纤维的孔隙率和崩解性。用不同的商业纤维素酶混合物测试了预处理稻草的消化率。我们发现经过预处理的稻草更容易受到酶水解，葡聚糖转化率比未经处理的稻草高 30-70%。纤维素水解的程度很大程度上取决于酶的种类及其配方。

• 强调

• 在稻草上培养B.firmus K-1 可去除约 21% 的木聚糖。

• 粒径（1-5 毫米）对木聚糖去除效率的影响可以忽略不计。

• 预处理生物质中葡聚糖转化的程度取决于酶制剂。