Improved Efficiency of Brewer’s Spent Grain Arabinoxylans by Ultrasound-Assisted Extraction

Arabinoxylan (AX) rich extracts from brewer’s spent grain (BSG) were produced by the application of ultrasound-assisted extraction (UAE) and conventional alkaline extraction (AKE). UAE and AKE were optimised for the production of the highest yield of ethanol insoluble material using response surface methodology (RSM). The efficiency of UAE was established by the significant reduction of time (7h to 25 min) and energy when compared to AKE, to recover similar amount of AX (60%) from BSG, leading to the production of starch-free AX-rich extracts

Xylanase and β-xylosidase production by Aspergillus ochraceus: new perspectives for the application of wheat straw autohydrolysis liquor

The xylanase biosynthesis is induced by its substrate—xylan. The high xylan content in some wastes such as wheat residues (wheat bran and wheat straw) makes them accessible and cheap sources of inducers to be mainly applied in great volumes of fermentation, such as those of industrial bioreactors. Thus, in this work, the main proposal was incorporated in the nutrient medium wheat straw particles decomposed to soluble compounds (liquor) through treatment of lignocellulosic materials in autohydrolysis process, as a strategy to increase and undervalue xylanase production by Aspergillus ochraceus. The wheat straw autohydrolysis liquor produced in several conditions was used as a sole carbon source or with wheat bran. The best conditions for xylanase and β-xylosidase production were observed when A. ochraceus was cultivated with 1% wheat bran added of 10% wheat straw liquor (produced after 15 min of hydrothermal treatment) as carbon source. This substrate was more favorable when compared with xylan, wheat bran, and wheat straw autohydrolysis liquor used separately. The application of this substrate mixture in a stirred tank bioreactor indicated the possibility of scaling up the process to commercial production.This work was supported by Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP/Brazil), Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq/Brazil), National System for Research on Biodiversity (SISBIOTA-Brazil, CNPq 563260/2010-6/FAPESP no. 2010/52322-3), and Fundacao para a Ciencia e a Tecnologia (FCT/Portugal)

Fungal enzyme sets for plant polysaccharide degradation

Enzymatic degradation of plant polysaccharides has many industrial applications, such as within the paper, food, and feed industry and for sustainable production of fuels and chemicals. Cellulose, hemicelluloses, and pectins are the main components of plant cell wall polysaccharides. These polysaccharides are often tightly packed, contain many different sugar residues, and are branched with a diversity of structures. To enable efficient degradation of these polysaccharides, fungi produce an extensive set of carbohydrate-active enzymes. The variety of the enzyme set differs between fungi and often corresponds to the requirements of its habitat. Carbohydrate-active enzymes can be organized in different families based on the amino acid sequence of the structurally related catalytic modules. Fungal enzymes involved in plant polysaccharide degradation are assigned to at least 35 glycoside hydrolase families, three carbohydrate esterase families and six polysaccharide lyase families. This mini-review will discuss the enzymes needed for complete degradation of plant polysaccharides and will give an overview of the latest developments concerning fungal carbohydrate-active enzymes and their corresponding families

UV tagging leaves the structural integrity of an arabino-(4-0-methylglucurono)xylan polysaccharide unaffected

The ultracentrifuge is a useful tool for probing the effects of chemical or other types of substitution/mutation in macromolecules, although very few studies have been performed on polysaccharides. In this study we demonstrate that the substitution of hydroxyl groups on the polysaccharide xylan by p-carboxy-benzyl (CB) bromide groups has little observed effect on molecular weight and little apparent effect on conformation (as monitored by sedimentation velocity and intrinsic viscosity). Corn-cob arabino-(4-O-methylglucurono)xylan (AGX) and its chemically modified derivative CB-AGX were found to have intrinsic viscosities of (82.8 ± 0.4) ml/g and (77.6 ± 0.5) ml/g, respectively. Sedimentation coefficients, s20,w0, were calculated to be (1.72 ± 0.06) S and (1.77 ± 0.06) S and (weight-average) molecular weights, Mw, from sedimentation equilibrium were found to be (37000 ± 1500) g/mol and (40000 ± 3000) g/mol. From these results we concluded that the UV tagging of arabinoxylan AGX does not significantly change the structural integrity of the xylan molecule; however, the decrease in intrinsic viscosity may indicate a very slight conformational change. © Springer-Verlag 1999