Production of ethanol by thermophilic oligosaccharide utilising Geobacillus thermoglucosidasius TM242 using palm kernel cake as a renewable feedstock
Production of ethanol by thermophilic oligosaccharide utilising Geobacillus thermoglucosidasius TM242 using palm kernel cake as a renewable feedstock
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DOI：
10.1016/j.biombioe.2016.08.015
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发表时间：
2016-12-01
影响因子：
6
通讯作者：
Leak, David J.
中科院分区：
文献类型：
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作者：
Raita, Marisa;Ibenegbu, Christopher;Leak, David J.
棕榈仁饼 (PKC) 是棕榈油加工过程中富含甘露聚糖的副产品，有潜力在生物精炼厂中转化为燃料和化学品。然而，甘露聚糖生物降解所需的关键酶甘露聚糖酶往往会产生短链甘露糖寡聚物，其需要通过甘露糖苷酶进一步转化，然后所得单体才能被大多数产乙醇者使用。在本研究中，Geobacillus therrnoglucosidasius TM242是一种能够利用短链寡糖的工程嗜热产乙醇菌，用于从富含甘露糖低聚物的PKC水解产物中生产乙醇，无需补充甘露糖苷酶，具有高乙醇转化效率。最高量的可发酵糖为 28.34 +/- 0.06 g/L，取自 5% (w/w) PKC，通过在 4.5 bar 下蒸汽爆破 15 分钟，然后使用 17.9 Ljig 甘露聚糖的 SEB 甘露聚糖和 10.4 FPU/g 葡聚糖的 CTec2 纤维素酶进行酶水解。 TM242 在 60 摄氏度下发酵 PKC 水解产物 48 小时，得到的最大乙醇浓度为 9.9 +/- 0.4 gL，相当于基于 PKC 中总可转化糖的理论产量的 92 +/- 2%。这明显高于使用酿酒酵母（35.4%）使用在相同条件下水解的 PKC 或高压灭菌器处理的 PKC 获得的结果（P < 0.05）。所开发的工艺对于从富含甘露聚糖的废物生产乙醇具有吸引力，因为它需要温和的预处理条件，并且避免在水解步骤中补充β-甘露糖苷酶，并利用底物中的所有糖类型和寡糖。 (C) 2016 Elsevier Ltd. 保留所有权利。
Palm kernel cake (PKC) is a mannan rich by-product from palm oil processing with potential for conversion to fuels and chemicals in biorefineries. However, mannanase, the key enzyme required for the biodegradation of mannan tends to produce short chain mannose oligomers which need further conversion by mannosidases before the resulting monomers can be used by most ethanologens. In this study, Geobacillus therrnoglucosidasius TM242, an engineered thermophilic ethanologen capable of utilising short-chain oligosaccharides was used for production of ethanol from a PKC hydrolysate rich in mannose oligomers without mannosidase supplementation, with high ethanol conversion efficiency. The highest amount of fermentable sugars of 28.34 +/- 0.06 g/L was obtained from 5% (w/w) PKC pretreated by steam explosion at 4.5 bar for 15 min followed by enzymatic hydrolysis using 17.9 Ljig mannan of SEB mannanase and 10.4 FPU/g glucan of CTec2 cellulase. Fermentation of the PKC hydrolysate by TM242 at 60 degrees C for 48 h gave a maximum ethanol concentration of 9.9 +/- 0.4 giL, equivalent to 92 +/- 2% of the theoretical yield based on the total convertible sugars in PKC. This was considerably higher than that obtained using Saccharomyces cerevisiae (35.4%) using PKC hydrolysed under the same conditions or the autoclave treated PKC (P < 0.05). The process developed is attractive for ethanol production from mannan-rich wastes as it requires mild pretreatment conditions and avoids beta-mannosidase supplementation in the hydrolysis step with utilization of all sugar types and oligosaccharides in the substrate. (C) 2016 Elsevier Ltd. All rights reserved.