Overproduction of Bioethanol From Cellulosic Wastes

Abstract

One of the most attractive lignocellulosic feedstock for the production of newlinebioethanol is the rice straw because of its cheaper and most abundantly found in newlinenature. Adding to it, it has high cellulose content that can be hydrolyzed into sugars newlineupon fermentation. The presence of lignin in the raw material makes it inferior in the newlineprocess of conversion of rice straw to bioethanol. Thus, selection of a suitable newlinepretreatment method that is cost-effective and which takes less time needs to be newlinedeveloped. Also, enzymatic hydrolysis is an essential step for degrading rice straw newlineinto fermentable sugars. Currently, for industrial bioethanol production, reseachers newlineare depending on the commercial enzymes that are quite expensive. Development of newlineinexpensive enzymes that can improve the parameters of hydrolysis is quite newlinenecessary. Finally, the heart in bioethanol production is the fermentation and newlinemicroorganisms such as yeasts are able to produce bioethanol in industrial scale. For newlinethis purpose, isolation of potential yeasts strains for obtaining maximum bioethanol newlineyield is required. newlineHence, in the present piece of work, we have isolated yeast species and newlinebased on biochemical, morphological and molecular analysis, the potential isolates newlinewere identified as Saccharomyces cerevisiae and Hanseniaspora guilliermondii. The newlineoptimum conditions for bioethanol production were also investigated. The newlineincubation time of 72 h was found to be best for bioethanol production by the best newlineisolate and maintaining the temperature and pH at 30°C and 4.5 respectively was newlinefound optimum. Physical treatment by grinding and milling followed by 4% NaOH newlinealkali treatment was found to be the best pretreatment technique and was newlineinvestigated by the FTIR, XRD and SEM analysis. Another fungus isolates which newlinewas identified as Aspergillus flavus was checked for its hydrolysis efficiency and newlinewas found the ability to produce cellulose enzyme. However, use of commercial newlineenzymes was found to be more efficient. The extracted bioethanol was analysed by newlinethe newline1 newlineH NMR and newline13 newlineC which confirms the presence of bioethanol. Strain newlineimprovement was done by mutagenesis which involves exposing the newlinemicroorganisms to UV rays and chemical mutagens such as EtBr and EMS. The newlinebioethanol yield of the wild strain (21.77%) was compared with that of the mutant newlinestrain (24.29%) which was achieved on treatment with EMS. Also, treatment with newlineEtBr also resulted in giving higher bioethanol yield but was found that not all the newlinemutants produced higher yields. Thus, searching for a favorable strain for improving newlinebioethanol production is in dire need. newline