Guo Haipeng, Hong Chuntao, Zheng Bingsong, Lu Fan, Jiang Dean, Qin Wensheng
Department of Biology, Lakehead University, Thunder Bay, ON P7B 5E1 Canada.
State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, 310058 China.
Biotechnol Biofuels. 2017 Dec 20;10:306. doi: 10.1186/s13068-017-0987-6. eCollection 2017.
Bioflocculation has been developed as a cost-effective and environment-friendly method to harvest multiple microalgae. However, the high production cost of bioflocculants makes it difficult to scale up. In the current study, low-cost bioflocculants were produced from untreated corn stover by a biomass-degrading bacterium sp. GO2.
sp. GO2 showed excellent production ability of bioflocculants through directly hydrolyzing various biomasses. The untreated corn stover was selected as carbon source for bioflocculants' production due to its highest flocculating efficiency compared to that when using other biomasses as carbon source. The effects of fermentation parameters on bioflocculants' production were optimized via response surface methodology. According to the optimal model, an ideal flocculating efficiency of 99.8% was obtained with the fermentation time of 130.46 h, initial pH of 7.46, and biomass content of 0.64%. The relative importance of carboxymethyl cellulase and xylanase accounted for 51.8% in the process of bioflocculants' production by boosted regression tree analysis, further indicating that the bioflocculants were mainly from the hydrolysates of biomass. Biochemical analysis showed that it contained 59.0% polysaccharides with uronic acid (34.2%), 32.1% protein, and 6.1% nucleic acid in the bioflocculants, which had an average molecular weight as 1.33 × 10 Da. In addition, the bioflocculants showed the highest flocculating efficiency at a concentration of 12.5 mg L and were stable over broad ranges of pH and temperature. The highest flocculating efficiencies obtained for and were 77.9 and 88.9%, respectively.
The results indicated that sp. GO2 can directly utilize various untreated lignocellulolytic biomasses to produce low-cost bioflocculants, which showed the high efficiency to harvest two green microalgae in a low GO2 fermentation broth/algal culture ratio.
生物絮凝作为一种经济高效且环境友好的方法已被开发用于收获多种微藻。然而，生物絮凝剂的高生产成本使其难以扩大规模。在本研究中，一种生物质降解细菌sp. GO2从未经处理的玉米秸秆中生产出低成本的生物絮凝剂。
sp. GO2通过直接水解各种生物质表现出优异的生物絮凝剂生产能力。与使用其他生物质作为碳源相比，未经处理的玉米秸秆因其最高的絮凝效率而被选作生物絮凝剂生产的碳源。通过响应面法优化了发酵参数对生物絮凝剂生产的影响。根据最优模型，在发酵时间为130.46小时、初始pH为7.46、生物质含量为0.64%的条件下，获得了99.8%的理想絮凝效率。通过增强回归树分析，羧甲基纤维素酶和木聚糖酶在生物絮凝剂生产过程中的相对重要性占51.8%，进一步表明生物絮凝剂主要来自生物质的水解产物。生化分析表明，生物絮凝剂中含有59.0%的多糖（含糖醛酸34.2%）、32.1%的蛋白质和6.1%的核酸，其平均分子量为1.33×10 Da。此外，生物絮凝剂在浓度为12.5 mg/L时表现出最高的絮凝效率，并且在较宽的pH和温度范围内稳定。对 和 获得的最高絮凝效率分别为77.9%和88.9%。
结果表明，sp. GO2可以直接利用各种未经处理的木质纤维素生物质来生产低成本的生物絮凝剂，其在低GO2发酵液/藻类培养比例下对收获两种绿色微藻具有高效率。
