Lignocellulosic biomass is abundant and low-cost, and has great potential in ethanol production.High temperature fermentation technology with high tolerance to multi-stresses has become a growing interest in lignocelluloses-to-ethanol production in terms of cost effective bioprocesses. Therefore, thermotolerant microorganisms that have a high tolerance for fermentation inhibitors are desirable.

Prof. LIU Chunzhao’s group from the Institute of Process Engineering (IPE), Chinese Academy of Sciences (CAS) made a progress on the selection and application of thermotolerant yeasts that were suitable for ethanol production from lignocelluloses. A new thermotolerant yeast strain of I. orientalis IPE 100 with good tolerances to temperature, ethanol, and lignocellulosic inhibitors was isolated and identified. This strain presented high efficiency of ethanol productivity at elevated temperature of 42 oC.

In their further study, Prof. Liu and his colleagues developed an efficient deep-bed SSF of sweet sorghum stalk to bioethanol with the thermotolerant strain IPE 100. The strain IPE 100 exhibited better performance for deep-bed solid state fermentation (SSF) of sweet sorghum stalk than others reported before. The deep-bed SSF significantly increased the loading efficiency of the fermented substrate in the bioreactor for achieving cost-effective way to produce ethanol.

Results in this research provided the prerequisite basis for industrial application of the isolated stain for efficient simultaneous saccharification and fermentation of lignocellulosic biomass due to both improvement of enzymatic hydrolysis at elevated temperatures and reduction of the pretreatment cost for detoxification. In addition, the developed process showed great potential for large-scale deep-bed SSF in practice. The main findings have been published on Bioresource Technology (doi:10.1016/j.biortech.2011.06.035 & doi:10.1016/j.biortech.2011.09.103).