School of Life Science and Biotechnology, Dalian University of Technology, Dalian, China.
J Appl Microbiol. 2012 Jan;112(1):38-44. doi: 10.1111/j.1365-2672.2011.05171.x. Epub 2011 Nov 1.
Developing an innovative process for ethanol fermentation from Jerusalem artichoke tubers under very high gravity (VHG) conditions.
A consolidated bioprocessing (CBP) strategy that integrated inulinase production, saccharification of inulin contained in Jerusalem artichoke tubers and ethanol production from sugars released from inulin by the enzyme was developed with the inulinase-producing yeast Kluyveromyces marxianus Y179 and fed-batch operation. The impact of inoculum age, aeration, the supplementation of pectinase and nutrients on the ethanol fermentation performance of the CBP system was studied. Although inulinase activities increased with the extension of the seed incubation time, its contribution to ethanol production was negligible because vigorously growing yeast cells harvested earlier carried out ethanol fermentation more efficiently. Thus, the overnight incubation that has been practised in ethanol production from starch-based feedstocks is recommended. Aeration facilitated the fermentation process, but compromised ethanol yield because of the negative Crabtree effect of the species, and increases the risk of contamination under industrial conditions. Therefore, nonaeration conditions are preferred for the CBP system. Pectinase supplementation reduced viscosity of the fermentation broth and improved ethanol production performance, particularly under high gravity conditions, but the enzyme cost should be carefully balanced. Medium optimization was performed, and ethanol concentration as high as 94·2 g l(-1) was achieved when 0·15 g l(-1) K(2) HPO(4) was supplemented, which presents a significant progress in ethanol production from Jerusalem artichoke tubers.
A CBP system using K. marxianus is suitable for efficient ethanol production from Jerusalem artichoke tubers under VHG conditions.
Jerusalem artichoke tubers are an alternative to grain-based feedstocks for ethanol production. The high ethanol concentration achieved using K. marxianus with the CBP system not only saves energy consumption for ethanol distillation, but also significantly reduces the amount of waste distillage discharged from the distillation system.
开发一种在超高浓度（VHG）条件下从菊芋块茎中发酵乙醇的创新方法。
采用菊粉酶生产、菊芋块茎中菊粉的糖化以及酶解菊粉生成的糖发酵生产乙醇的整合生物加工（CBP）策略，利用产菊粉酶酵母 Kluyveromyces marxianus Y179 和分批补料操作进行。研究了接种龄、通气、果胶酶和营养物补加对 CBP 系统乙醇发酵性能的影响。虽然随着种子培养时间的延长，菊粉酶活性增加，但对乙醇生产的贡献可以忽略不计，因为更早收获的生长旺盛的酵母细胞能更有效地进行乙醇发酵。因此，推荐在以淀粉为原料的发酵生产中使用过夜培养。通气有利于发酵过程，但由于该物种的负 Crabtree 效应，会降低乙醇产率，而且在工业条件下增加污染的风险。因此，非通气条件更适合 CBP 系统。果胶酶补加降低了发酵液的黏度，提高了乙醇生产性能，特别是在高浓度条件下，但应仔细平衡酶的成本。对培养基进行了优化，当补加 0.15 g/L 的 K2HPO4 时，乙醇浓度高达 94.2 g/L，这在菊芋块茎发酵生产乙醇方面取得了显著进展。
在 VHG 条件下，利用 K. marxianus 的 CBP 系统适合从菊芋块茎中高效生产乙醇。
菊芋块茎是替代基于谷物的原料生产乙醇的一种选择。使用 K. marxianus 的 CBP 系统获得的高乙醇浓度不仅可以节省乙醇蒸馏的能耗，而且还可以显著减少从蒸馏系统排放的废蒸馏馏分的量。
