ONOPORDUM-NERVOSUM AS BIOMASS SOURCE - SOME ASPECTS OF ITS PRODUCTIONAND TRANSFORMATION BY ENZYMATIC-HYDROLYSIS

Onopordum nervosum, a lignocellulosic herbaceous species of the Iberia n Peninsula, has been selected as a suitable biomass source to be used in transformation processes to obtain energetic or industrial product s. In this work, the effectiveness of different chemical pretreatments as a preliminary step to the enzymatic hydrolysis of this lignocellul osic biomass was evaluated. In order to determine biomass productivity , field assays were carried out in 1988 and 1989 using different plant ing densities and evaluating the effect of top fertilization. Biomass yields between 12 and 20 t ha-1 were obtained, depending on the year a nd the planting density assayed. No significant differences were found in production rates when top fertilization was applied. Enzymatic hyd rolysis of O. nervosum using a cellulolytic complex from Trichoderma l ongibrachiatum QM9414, gave low yields when untreated lignocellulosic biomass was used as substrate. Among different chemical pretreatments tested, ethanol and butanol solubilizations in the presence of a basic catalyst gave the best results. For the most effective pretreatment c onditions, a delignification of about 30% and a complete recovery of g lucose in the treated substrate were obtained both for butanol and eth anol. The highest enzymatic hydrolysis yields were found when ethanol was used as solvent, giving a saccharification efficiency of about 66% which, compared to the 23% for the native substrate, indicates the re markable increment in the susceptibility of the cellulose to enzyme at tack effected by this pretreatment.