Production of biobutanol from rice straw: An overview on pretreatment, hydrolysis, and fermentation

Rice straw is a promising agricultural residue for the production of biobutanol due to its plentitude and low commercial value. Rice straw has high potential sugars that can be converted into fermentable sugars. However, biobutanol production from rice straw-based on the current technology is not economically viable due to the challenges and restrictions throughout the overall process of rice straw-biobutanol conversion. For the process to be economically viable, the use of an appropriate pretreatment technique is of great significance since an effective pretreatment can result in efficient hydrolysis. In this article, a total number of 66 articles from 1980-2018 were first searched on databases using keywords and then were reviewed. This paper reviews the current approaches and advances available for the production of biobutanol from rice straw. The challenges encountered throughout the overall process of bioconversion of rice straw into biobutanol are discussed as well. Even though much attempt has been made to develop a proper technique for pretreatment of rice straw, efforts are still required to make the process more efficient and economically feasible. The use of genetically modified butanol tolerant strains has resulted in butanol production at higher concentrations. Therefore, in situ product-recovery systems have become more economical as substrate inhibition and butanol toxicity to the culture are drastically reduced.