Romanian Biotechnological Letters Vol. 16, No.1, 2011, Supplement Copyright © 2011 University of Buchare Printed in Romania. All rights reserved ORIGINAL PAPER 106 Simultaneous hydrolysis and fermentation of lignocellulose versus separated hydrolysis and fermentation for ethanol production Received for publication, November 5, 2010 Accepted, February 9, 2011 TEODOR VINTILĂ 1 , DANIELA VINTILĂ 1 , SIMINA NEO 1 , CAMELIA TULCAN 1 , NICOLETA HADARUGA 1 1 University of Agricultural Science and Veterinary Medicine, Timişoara, România Corresponding author: Teodor Vintila, e-mail: tvintila@animalsci-tm.ro, Tel. 004(0)256277086, Calea Aradului nr. 119, Timisoara 300645, Romania Abstract Second generation of biofuels relay mostly on lignocellulose as raw materials. There are several technologies applied to obtain ethanol from lignocellulose. In this study we try to compare the productivity and efficiency of two technologies: simultaneous hydrolysis (saccharification) and fermentation (SSF) and separated hydrolysis and fermentation (SHF). We used a BlueSens equipment with CO 2 ant EtOH cap sensors mounted on the fermentation flasks. In the first part we have studied how the size and type of inoculums and agitation influence the production o ethanol. In the next steps, we applied the two technologies to hydrolyze and ferment different types of cellulose from agriculture. The biomass was pretreated using alkaline and steam combined method. The cellulases used for hydrolysis are Trichoderma cellulases Onozuka from Merk, Aspergillus cellulases from Fluka, and cellobiase from Novo. The results show that the type of the yeasts is very important, especially for SSF technology, where high temperature is applied to ferment and hydrolyze in the same time. Also, the size of inoculums influence the speed of fermentation. Regarding the rate of hydrolysis and ethanol production, in case of Avicel cellulose, the hydrolysis rate is between 21 – 24% (in a fermentation medium of 10% cellulose). As for wheat straw and corn stalks, the rate of hydrolysis is much higher, over 80%. The ethanol production from lignocellulosic biomass is higher in SSF than in SHF. The results indicate that SSF is more efficient that SHF in terms of total production time, energy consumption and total production costs. Key words: lignocellulose, hydrolysis, fermentation, ethanol Introduction Lately, the concentration of gases that retain parts of the radiation from the sun has increased, and the result is an increased green house effect and therefore global warming. By using bioethanol instead of petrol the emissions of green house gases decreases. The cellulose in biomass can be hydrolyzed to sugars that can be fermented into ethanol. Wheat straw and corn stalks has a rather large content of cellulose, roughly 34-45 % [1,2]. Different processes and technologies applied over the time to convert cellulose to ethanol indicate a wide range of productivity and efficiency, some authors reporting between 150 and 280 liters of ethanol / dry ton of lignocellulosic biomass [3,4,5,6]. The aims of this study were to evaluate the capacity of some local yeast strains and cellulases to work in similar conditions and to compare the productivity and efficiency of two technologies: simultaneous saccharification (hydrolysis) and fermentation (SSF) and separated hydrolysis and fermentation (SHF) applied to convert wastes from agriculture to ethanol. Materials and methods 1. Yeasts selection. The optimal temperature for the highest enzymatic activity of cellulases was established in previous studies [7,8], and is around 50 o C. Yeasts ferment sugars