2nd INTERNATIONAL CONFERENCE On
FRONTIERS IN BIOLOGICAL SCIENCES (lnCoFIBS-2015)
22nd to 24th January, 2015
Organized by
Department of Life Science
4 Hk.
NATIONAL INSTITUTE OF TECHNOLOGY
ROURKELA. ODISHA. INDIA
Invited Lecture - Bioremediation, Biomass and Bioenergy
Ethanol from rice straw: Optimization of process protocols using two stage microbial systems
Arpan Das', Miklós Takó:, Csaba Vagvolgyi2 and Keshab C. Mondái1*
D epartm ent o f M icrobiology, V idyasagar University, M idnapore - 721102, West Bengal, India
'Dept, o f M icrobiology, U niversity o f Szeged, H-6726 Szeged, H ungary
*E-mail: mondalkc@gmail.com
ABSTRACT
Energy consumption has increased steadily as world population has grown and concerns about atmospheric pollution derived from fossil fuels. This has raised worldwide interest in exploring renewable energy from biomass. The conversion of biomass into biofuels in the form of ethanol has drawn much attention in the last decades. Second-generation bioethanol obtained from lignocellulosic materials, including agricultural, forest residues and woody crops, has received major attention due to their abundance and immense potential for conversion into sugars and fuels.
Rice straw is one o f the most abundant agricultural by-products, having low commercial value and most of it is being used as cattle feed and waste. The major constituents o f rice straw are 41.2% cellulose, 31.7% hemicellulose, and 21.8%
lignin, which indicate the presence o f large amount o f fermentative sugar. The major barrier for production o f ethanol from rice straw is that, in it cellulose is tightly bound to hemicelluloses and lignin, and also abundance of silicate. Lignin resists degradation and confers hydrolytic stability and structural robustness to the cell walls of the straw. To overcome lignocellulose recalcitrance, pretreatment is required to facilitate the enzymatic hydrolysis o f the carbohydrate fraction to monomeric sugars.
Considering this, a multidimensional approach for ethanol production from rice straw was opted by three distinct phases: first, statistical optimization o f (3- glucosidase production from co-culture o f Aspergillus fumigatus ABK9 and Trichoderma reesei SAF3 through mixed substrate (wheat bran and rice straw) fermentation; secondly, enzymatic saccharification of pretreated (with 1% NaOH) rice straw for yielding o f reducing sugars, and finally, optimization o f bioconversion of the sugar to ethanol by mixed culture fermentation of Saccharomyces cerevisiae MTCC 173 and Zymomonas mobilis MTCC 2428. In optimized condition, maximum fTglucosidase yield o f 265.4 U g"1 was achieved. Enzymatic treatment (40 U g ') of NaOH pretreated rice straw produced maximum reducing sugar o f 24.9 g L .It also showed maximum enzyme adsorption (E ^ J by 2 fold and decreased the absorption coefficient (K^) by 37.64% relative to untreated straw. During ethanol fermentation, yeast: bacteria ratio (1.53) became most influencing factor to maximize ethanol production o f 40.1 g L ', indicating the influencing effect o f the perpetrator strains.
lnC oFIBS-2015, 22nd to 24th Janu ary 2015, Department of Life Scien ce, NIT R ourkela, O d ish a, India [Page 33]
