Department of Chemical Engineering, Ryerson University, Toronto, ON, M5B 2K3, Canada.
Bioprocess Biosyst Eng. 2013 Nov;36(11):1735-43. doi: 10.1007/s00449-013-0948-9. Epub 2013 Apr 5.
The present study demonstrates the ability to produce green biocellulose nanofibers using the renewable resources of agriculture residues. Locally grown wheat straws (WS) were hydrolyzed under different conditions. Their hydrolysates were utilized to produce the nanofibers in separate hydrolysis fermentation process by Gluconacetobacter xylinus strain bacterium. Highest biocellulose production of ~10.6 g/L was achieved with samples that were enzymatically hydrolyzed. Moreover, acidic hydrolyzed WS produced up to 9.7 g/L, with total sugar concentrations in culture media of 43 g/L. Generally, enzymatic hydrolysis of WS resulted in more total sugar concentration than the acidic hydrolysis (i.e., 52.12 g/L), while water hydrolysis produced the least. This can be related to utilizing Xylanase in addition to Cellulase and Beta-glucosidase that helps to hydrolyse WS dry basis of cellulose and hemicelluloses. Sugar mixtures produced under all hydrolysis conditions were mainly composed of glucose and xylose with average percentages of 56 and 28 %, respectively. Acidic hydrolysis at higher acid concentration, as well as soaking WS in the acidic solution for longer time, improved the total sugar concentration in the culture media by 18 %. Conducting thermal treatment at more intense conditions of higher temperature or heating time improved the total sugar produced with acidic hydrolysis. These conditions, however, resulted in further production of furfural, which considerably affected bacterial cells proliferation. This resulted in lowest sugar consumption in the range of 62-64 % that affected final BC production.
本研究展示了利用农业废弃物可再生资源生产绿色生物纤维素纳米纤维的能力。对当地种植的小麦秸秆（WS）在不同条件下进行水解。利用木醋酸杆菌菌株在单独的水解发酵过程中利用其水解物来生产纳米纤维。用酶水解的样品获得了最高的生物纤维素产量~10.6 g/L。此外，酸性水解的 WS 可产生高达 9.7 g/L 的生物纤维素，培养基中的总糖浓度为 43 g/L。一般来说，WS 的酶水解比酸性水解产生更多的总糖浓度（即 52.12 g/L），而水解产生的总糖浓度最少。这可能与使用木聚糖酶有关，木聚糖酶除了纤维素酶和β-葡萄糖苷酶外，还可以帮助水解 WS 干物质中的纤维素和半纤维素。在所有水解条件下产生的糖混合物主要由葡萄糖和木糖组成，平均百分比分别为 56%和 28%。在较高酸浓度下进行酸性水解，以及将 WS 在酸性溶液中浸泡更长时间，可将培养基中的总糖浓度提高 18%。在更强烈的高温或加热时间条件下进行热处理可提高酸性水解产生的总糖产量。然而，这些条件会导致糠醛的进一步产生，这会严重影响细菌细胞的增殖。这导致糖消耗率最低，范围为 62-64%，这会影响最终 BC 的产量。
