Microbial Production of Bioethanol from Gamma Irradiated Sugarcane Bagasse and Potato Peels

Abstract

ECENTLY, with growing crisis in fossil fuel and the ………consequent of environmental pollution problems worldwide, bioethanol has become one of the most promising biofuels and many researchers have worked on improving the efficacy of the bioethanol production process. This work was concerned with producing bioethanol from low-cost raw agro-industrial feedstock (sugarcane bagasse and potato peels) and utilizing radiation technology to increase conversion rate of these materials to bioethanol. Both of sugarcane bagasse and potato peels were acid-hydrolyzed and resulted hydrolysates were fermented by either Zymomonas mobilis ATCC 29191, Saccharomyces cerevisiae ATCC 7754, or both organisms, cocultured (1:1). The effect of gamma irradiation on bioethanol production was studied by exposing the feedstock to different doses of gamma rays (0, 25, 50 75 kGy). Effect on combining gamma irradiation with acid treatment of feedstock on bioethanol production was also investigated. From sugarcane bagasse, the highest achieved final bioethanol concentration (15.4 gL -1 ) was obtained from the combined pretreatment by irradiation with 75 kGy followed by hydrolysis with 2 % (v/v) H 2 SO 4 at 120°C for 60 min and fermented with co-culture (1:1) of Z. mobilis ATCC 29191 and Sacch. cerevisiae ATCC 29191. On the other hand, from potato peels the highest bioethanol concentration (12.1 g L -1 ) was obtained from combined pretreatment by irradiation with 75 kGy and hydrolyzed by 6 % (v/v) H 2 SO 4 at 100°C for 60 min then fermented with co-culture (1:1). Keywords:Saccharomyces cerevisiae ATCC 7754, Zymomonas mobilis ATCC 29191, Bioethanol, Feedstock, Gamma irradiation, Dilute acid hydrolysis.The rising concern over depleting fossil fuel and greenhouse gas limits has resulted in a high level of interest in non-conventional fuel originating from biorenewable sources including sugars, starches and lignocellulosic materials. The importance of the bioethanol production has increased in the last few years, but cost of production is still interfering with the deployment of this new technology, where the cost of used raw materials (sugar and starch-containing materials) represents about 40-70% of the total production cost. Using less valuable materials, like lignocellulosic agricultural waste, could significantly reduce the production