Abstract

Xylanolytic enzymes were produced by Aspergillus niger NRRL3 grown on agro-industrial by-products obtained from the processing of wheat flour without pretreatment. Significant parameters for xylanase production were screened and optimized. The xylanolytic activity obtained in the optimized extract was 138.3 ± 2.6 U/mL, higher than the activity obtained in an unoptimized medium (14.5 ± 0.3 U/mL) in previous work. The optimized fermentation process was performed in a successful 40-fold scale-up. The optimized enzymatic extract obtained was characterized by LC-MS. Nine enzymes were identified as constituents of the xylanolytic complex. Moreover, the xylanolytic enzymes were stable until 60 °C and over a broad range of pH. Sodium, calcium, cobalt and manganese had no inhibitory effect, meanwhile 1% w/v polyvinylpyrrolidone and 1% w/v dextran increased the xylanolytic activity. The saccharification efficiency was evaluated and the surface morphology of the lignocellulosic substrate was monitored by using scanning electron microscopy (SEM). The synergistic combination of the extracted (o purified) xylanolytic enzymes permitted a higher xylan conversion beneficial for diverse applications, such as bioethanol production. Thus, these agroindustrial by-products can be used within the framework of a circular economy, rendering an added value bioproduct, which is reused in the industry.

摘要

木糖酵解酶由黑曲霉产生NRRL3是在未经预处理的情况下生长于从小麦粉加工获得的农业工业副产品上的。筛选并优化了木聚糖酶生产的重要参数。在优化的提取物中获得的木聚糖水解活性为138.3±2.6 U / mL，高于先前工作中在未优化的培养基中获得的木聚糖水解活性（14.5±0.3 U / mL）。优化的发酵过程以成功的40倍放大进行。通过LC-MS表征获得的优化的酶提取物。九种酶被鉴定为木聚糖分解复合物的成分。此外，木聚糖分解酶在60°C的温度范围和广泛的pH范围内都稳定。钠，钙，钴和锰没有抑制作用，同时1％w / v聚乙烯吡咯烷酮和1％w / v葡聚糖增加了木聚糖分解活性。评价糖化效率，并通过使用扫描电子显微镜（SEM）监测木质纤维素底物的表面形态。提取的（经纯化的）木聚糖分解酶的协同作用可提高木聚糖的转化率，有利于多种应用，例如生物乙醇的生产。因此，这些农业工业副产品可以在循环经济的框架内使用，从而提供了增值的生物产品，可在工业中重复使用。