Production from hemicellulosic

The Purdue concepts have been applied to several different agricultural products, such as corn stalks, alfalfa, orchard grass, tall fescue, and sugarcane bagasse. No experiments have been reported on either hardwoods or softwoods. The processes have been explored in two major modes. In the first, the entire agricultural residue is treated with solvent in the second, a dilute acid pretreatment to remove hemicellulose precedes solvent treatment. The first process is especially desirable for making furfural or fermentation products from hemicellulose as a separate activity. Then, the hemicellulose-free raw material can be converted to substantially pure glucose. 

Sakamoto T, Hasunuma T, Hori Y, Yamada R, Kondo A. (2011). Direct ethanol production from hemicellulosic materials of rice straw by use of an engineered yeast strain codisplaying three types of hemicellulolytic enzymes on the surface of xylose-utilizing Sacchammyces cerevisiae cells. J Biotechnol, 158, 203-210. 

Bustos G, Moldes AB, Cruz JM, Dominguez JM. (2005). Influence of the metabolism pathway on lactic acid production from hemicellulosic trimming vine shoots hydrolyzates using Lactobacillus pentosus. Biotechnol Prog, 21, 793-798. 

Cane and beet sugars can be extracted in almost pure form and used as highly reactive chemical intermediates or for edible purposes. Ntuaerous other sugars have been extracted from plant products or produced as hydrolysis products from hemicelluloses, celluloses, and starches. 

Lopes M, Rocha R, Zanotto S, Gomez J, Silva L (2009) Screening of bacteria to produce polyhydroxyalkanoates from xylose. World J Microbiol Biotechnol 25(10) 1751-1756 Lopes MSG, Freire RKB, Chouman K, Gomez JGC, da Silva LF (2010) Engineered bacteria For PHB production from hemicellulosic hydrolysate. In International symposium on biopolymers, Stuttgart, p 72... 

Xylan-type polysaccharides are the main hemicellulose components of secondary cell walls constituting about 20-30% of the biomass of dicotyl plants (hardwoods and herbaceous plants). In some tissues of monocotyl plants (grasses and cereals) xylans occur up to 50% [6j. Xylans are thus available in huge and replenishable amoimts as by-products from forestry, the agriculture, wood, and pulp and paper industries. Nowadays, xylans of some seaweed represent a novel biopolymer resource [4j. The diversity and complexity of xylans suggest that many useful by-products can be potentially produced and, therefore, these polysaccharides are considered as possible biopolymer raw materials for various exploitations. As a renewable resource, xylans are... 

However, most of these routes are still economically unattractive and the possibility of creating an equivalent petrochemistry based on biomass, which depends on raising the conversion efficiency and establishing cascades in which the residues of one product serve as inputs for another, still suffers from the relatively unattractive products derived from hemicellulose and lignin. Therefore, to bring back biomass into the chemical business , the utilization of biomass must be enhanced by integrating it into biorefinery (Fig. 2). 

Fig. 7. The major decomposition products from burning of cellulose. Levoglucosan is the dominant compound, and mannosan and galactosan are formed as well as levoglucosan from burning of hemicelluloses.

Levulinic acid is formed by the treatment of six-carbon sugar carbohydrates from starch or lignocellulosics with acids, or by add treatment plus a reductive step of five-carbon sugars derived from hemicellulose. Levulinic add can serve as a building block for the synthesis of many derivatives of interest may be the selective oxidation to succinic and acrylic add. [i-Acetylacrylic add could be used in the production of new acrylate polymers. 

Apart from hemicellulose and cellulose, lignin is also a promising raw material for various applications. Huttermann et al. (2001) described various potential technologies for lignin modification for the production of new compounded materials. Pan et al. (2005) demonstrated that lignin extracted during ethanol organosolv... 

Buchert, J., Puls, J. andPoutanen, K. 1988. Comparison of Pseudomonas Fragi and Gluconobac-ter Oxydans for Production of Xylonic Acid from Hemicellulose Hydrolyzates. Appl. Microbiol. Biotechnol., 28, 367-372. 

When screening a large number of Lactobacillus strains for lactate production using hemicellulose hydrolysate, strains L. pentosus CHCC2355 and L. brevis CHCC2097 were selected and evaluated further (Garde et al, 2002). Each strain produced lactate with 88% (for L. pentosus) and 61% of the theoretical yield (L. brevis), respectively, from wheat straw hydrolysate without visible inhibition. The operation of the phosphoketolase pathway in these... 

Garde, A., Jonsson, G., Schmidt, A. S., and Ahring, B. K. 2002. Lactic acid production from wheat straw hemicellulose hydrolysate by Lactobacillus pentosus and Lactobacillus brevis. Bioresour. Technol., 81,217-223. 

Takahashi, R., Mizumoto, K., Tajika, K., and Takano, R., Production of oligosaccharides from hemicellulose of woody biomass by enzymatic-hydrolysis. 1. A simple method for isolating beta-D-mannanase-producing microorganisms. Mokuzai Gakkaishi 1992, 38 (12), 1126-1135. 

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