Department of Chemical Engineering, Ryerson University, Toronto, Ontario, Canada.
Appl Biochem Biotechnol. 2010 Nov;162(6):1647-59. doi: 10.1007/s12010-010-8946-8. Epub 2010 Apr 1.
In the present preliminary study, we report results for the biocellulose nanofibres production by Gluconacetobacter xylinus. Production was examined by utilizing different feedstocks of single sugars and sugar mixtures with compositions similar to the acid hydrolyzates of different agriculture residues. Profiles for cell proliferation, sugar consumption, and the subsequent pH changes were thoroughly analyzed. Highest biocellulose production of 5.65 g/L was achieved in fructose medium with total sugar consumption of 95.57%. Moreover, the highest production using sugar mixtures was 5.2 g/L, which was achieved in feedstock with composition identical to the acid hydrolyzate of wheat straws. This represented the highest biocellulose yield of 17.72 g/g sugars compared with 14.77 g/g fructose. The lowest production of 1.1 and 1.75 g/L were obtained in xylose and glucose media, respectively, while sucrose and arabinose media achieved relatively higher production of 4.7 and 4.1 g/L, respectively. Deviation in pH of the fermentation broths from the optimum value of 4-5 generally had marked effect on biocellulose production with single sugars in feedstock. However, the final pH values recorded in the different sugar mixtures were approximately 3.3-3.4, which had lower effect on production hindrance. Analyzing profiles for sugars' concentrations and cell growth showed that large amount of the metabolized sugars were mainly utilized for bacterial cell growth and maintenance, rather than biocellulose production. This was clearly observed with single sugars of low production, while sugar consumption was rather utilized for biocellulose production with sugar mixtures. Results reported in this study demonstrate that agriculture residues might be used as potential feedstocks for the biocellulose nanofibres production. Not only this represents a renewable source of feedstock, but also might lead to major improvements in production if proper supplements and control were utilized in the fermentation process.
在本初步研究中，我们报告了利用不同单糖和糖混合物作为原料生产纤维二糖纳米纤维的结果，这些糖混合物的组成与不同农业残余物的酸水解产物相似。我们详细分析了细胞增殖、糖消耗和随后 pH 值变化的情况。在果糖培养基中，最高生物纤维素产量为 5.65 g/L，总糖消耗为 95.57%。此外，使用糖混合物的最高产量为 5.2 g/L，这是在与小麦秸秆酸水解产物组成相同的原料中实现的。这代表了与 14.77 g/g 果糖相比，17.72 g/g 糖的最高生物纤维素得率。在木糖和葡萄糖培养基中，产量最低，分别为 1.1 和 1.75 g/L，而蔗糖和阿拉伯糖培养基的产量相对较高，分别为 4.7 和 4.1 g/L。发酵液的 pH 值偏离 4-5 的最佳值通常对单糖原料中的生物纤维素产量有显著影响。然而，不同糖混合物中记录的最终 pH 值约为 3.3-3.4，对生产抑制的影响较低。分析糖浓度和细胞生长的曲线表明，大量代谢糖主要用于细菌细胞的生长和维持，而不是生物纤维素的生产。这在低产量的单糖中表现得很明显，而在糖混合物中，糖消耗主要用于生物纤维素的生产。本研究报告的结果表明，农业残余物可用作生物纤维素纳米纤维生产的潜在原料。这不仅代表了可再生的原料来源，而且如果在发酵过程中利用适当的补充剂和控制，可能会导致产量的显著提高。
