%0 Journal Article
%T Ethanol and Volatile Fatty Acid Production from Lignocellulose by Clostridium cellulolyticum
%A K. Williams
%A Y. Zheng
%A J. McGarvey
%A Z. Fan
%A R. Zhang
%J ISRN Biotechnology
%D 2013
%R 10.5402/2013/137835
%X Clostridium cellulolyticum is capable of producing glycosyl hydrolase enzymes as well as fermentation products including ethanol and acetate. In this study, the potential of using C. cellulolyticum for ethanol and volatile fatty acid production from straw and grape pomace was examined. For rice straw, the effects of alkaline pretreatment and substrate sterilization prior to fermentation on products yields were also investigated. Effects of alkaline pretreatment and necessity for subsequent washing were tested for two types of grape pomace. For rice straw, the highest ethanol yield was 0.16£¿g/gVS from the straw pretreated with 10% sodium hydroxide loading at 1 2 1 ¡ã C for 1 hour. Sterilization of the straw prior to fermentation was found to be not significant for ethanol production. Sterilization appeared to decrease native acetogen populations in the rice straw, resulting in lower acetic acid yields. The highest ethanol yield from grape pomace was of 0.09£¿g/gVS from the pretreated pomace. Pomace type (red or white) and washing were found to be not significant. Ethanol yields by C. cellulolyticum were lower than those from yeast in a simultaneous saccharification and fermentation system, but overall conversion of cellulose and hemicellulose was high, between 68 and 79%. 1. Introduction Lignocellulosic biomass, including crop and forestry residues, grasses, and other plant materials, is currently the primary focus feedstock for bioethanol and biochemical production research. This study focused on two lignocellulosic substrates that are common in California: rice straw and grape pomace. In California, there are around 200,000 hectares of rice planted resulting in around 1.1 million tons of rice straw per year [1]. The rice straw is usually burned or tilled into the soil. Tilling can be cost intensive, and burning causes significant air pollution, which is highly regulated in California. An environmentally friendly and economic use for this agricultural residue is needed. The rice straw used in this study was composed of 16.8% lignin, 38.8% cellulose, 24.1% hemicellulose, and 20.4% ash on a dry basis with a moisture content of 5.8%. The hemicellulose fraction was made up of 83.3% xylose, 1.3% galactose, and 15.4% arabinose. Grape pomace is also abundant in California with around 150,000 dry tons of grape pomace produced each year in California [2]. There are two types of grape pomace: white (produced from grape crushing prior to fermentation) and red (resulted after fermentation). The white pomace used in this study contained 16% lignin, 8.9% cellulose,
%U http://www.hindawi.com/journals/isrn.biotechnology/2013/137835/