International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2016): 79.57 | Impact Factor (2017): 7.296 Volume 7 Issue 5, May 2018 www.ijsr.net Licensed Under Creative Commons Attribution CC BY Bioethanol Production from Saccharified Sweet Potato (Ipomoea batatas L.) Root Flour using Immobilized Cells of Saccharomyces cerevisiae and Zymomonas mobilis by RSM Method Preeti Krishna Dash 1 , Sonali Mohaptra 2 , Santi Lata Sahoo 3 , Hrudayanath Thatoi 4 1, 3 Department of Botany, Utkal University, Vani vihar, Bhubaneswar-751004, Odisha, India 2 Department of Biotechnology, College of Engineering and Technology, Biju Pattnaik University of Technology, Bhubaneswar-751003, India 4 Department of Biotechnology, North Orissa University, Sriram Chandra vihar, Takatpur, Baripada-757003, Odisha, India Abstract: With the increase in price of fossil fuels, the demand of bioethanol production from agricultural crops has become very crucial to meet the energy crisis in both developing and developed countries in future. Sweet potato is considered as an important agricultural crop due to its abundance and high amount of starch content. The present study focuses on bioethanol production from saccharified sweet potato root flour (SPRF) using co-immobilized cells of Saccharomyces cerevisiae and Zymomonas mobilis for bioethanol production by RSM method. The process parameters such as temperature, pH and incubation time were found to be the most favorable variables for the maximum ethanol production with box-behnken design of response surface methodology (RSM). Maximum ethanol of 90.6 g/kg of SPRF was obtained at pH 4.5 with an incubation period of 72 h at 32.5 °C by response surface methodology. Keywords: Sweet potato, Bioethanol production, Immobilization, Response surface methodology, Saccharomyces cerevisiae and Zymomonas mobilis 1. Introduction With the increasing demand for ethanol, there is a considerable interest in developing biorenewable alternatives to substitute fossil fuels from non- conventional raw materials. Bioethanol contributes to diminish petroleum dependency, has positive effects on the environment generate and also new opportunities in the agricultural and agro-industrial sectors [1]. Now-a-days establishment of ethanol industry requires a cheap and sufficiently available feedstock to reduce the production costs which has been recognized as a critical point [2]. To meet the sake of the win-win prospect between the energy production and food security, today the fuel industry requires non-grain energy crops and agricultural biomass for ethanol production [3]. As the tubers contain sufficient amount of starch, they may be a suitable substrate for ethanol production [4]. The tuber crops like cassava, potato, sweet potato are most promising feed stock used in bioethanol production in worldwide due to their economic viability and availability [5, 6]. Sweet potato (Ipomoea batatas L.) is a cheap and readily available tuber crop in the tropical and temperate regions’ in Indian sub-continent which mainly contains starch (178 g /kg), total sugars (26 g /kg) and protein (3.2 g/kg) on fresh weight basis [7]. As starch is a polysachharide, it can be hydrolysed to monomer units of carbohydrates for ethanol production by microorganisms in fermentation process [8]. The ethanol fermentation processes from starchy materials commonly involves two stages: (i) liquefaction of starch by a amylase (hydrolysis) enzyme and enzymatic saccharification of the low molecular weight liquefaction products such as dextrin to produce glucose by an glucoamylase (saccharification); (ii) fermentation of glucose to ethanol by ethanol producing microorganisms [9, 10]. The yeast, Saccharomyces cerevisiae, is the major ethanol producing microorganism has been used all over the world [11]. Zymomonas mobilis, is also an ethanol producing bacterium, as it shows several better fermenting characters like convertion of glucose to ethanol and CO 2, grows more rapidly and shows highest ethanol productivity at industrial- scale [12]. Now a days many researchers have been attempted to combine the two stage fermentation process in a single-step for bioethanol production but not on an industrial scale [13] because it is very difficult to optimize the conditions for one strain without affecting the other strains [14]. Therefore, co-immobilization different kinds of microorganisms within the same porous matrix and combination two stage fermentation process in a single-step used in bioethanol production which reduces the energy input and increases the efficiency of substrate utilization [15]. Response surface methodology (RSM) is an extensively used method in bioethanol production which comprises of a group of mathematical and statistical procedure that can be used to optimize different culture conditions in fermentation processes [16]. The model predicts experimental modifications like changes in operational conditions with minimum requirements and maximum yields [17]. The present work aims at developing a simultaneous single-step system for bioethanol fermentation from saccharified sweet potato, using co-immobilized cells of yeast S. cerevisiae and bacteria, Zymomonas mobilis by RSM for enhanced bioethanol production. Paper ID: ART20182132 DOI: 10.21275/ART20182132 305