Degradative actions of microbial xylanolytic activities on hemicelluloses from rhizome of Arundo donax.

Polysaccharidases from extremophiles are remarkable for specific action, resistance to different reaction conditions and other biotechnologically interesting features. In this article the action of crude extracts of thermophilic microorganisms (Thermotoga neapolitana, Geobacillus thermantarcticus and Thermoanaerobacterium thermostercoris) is studied using as substrate hemicellulose from one of the most interesting biomass crops, the giant reed (Arundo donax L.). This biomass can be cultivated without competition and a huge amount of rhizomes remains in the soil at the end of cropping cycle (10-15 years) representing a further source of useful molecules. Optimization of the procedure for preparation of the hemicellulose fraction from rhizomes of Arundo donax, is studied. Polysaccharidases from crude extracts of thermophilic microorganisms revealed to be suitable for total degradative action and/or production of small useful oligosaccharides from hemicelluloses from A. donax. Xylobiose and interesting tetra- and pentasaccharide are obtained by enzymatic action in different conditions. Convenient amount of raw material was processed per mg of crude enzymes. Raw hemicelluloses and pretreated material show antioxidant activity unlike isolated tetra- and pentasaccharide. The body of results suggest that rhizomes represent a useful raw material for the production of valuable industrial products, thus allowing to increase the economic efficiency of A. donax cultivation.

Enzymatic routes for the production of mono- and di-glucosylated derivatives of hydroxytyrosol.

In this work, a new eco-friendly procedure for the synthesis of hydroxytyrosol and tyrosol α-glycosidic derivatives was proposed by using the marine α-glucosidase from Aplysia fasciata, and a commercial tyrosinase from mushroom for the bioconversion of tyrosol glycosidic derivatives into the corresponding hydroxytyrosol products. New hydroxytyrosol mono- and di-saccharide derivatives were synthesized at final concentrations of 9.35 and 10.8 g/l of reaction, respectively, and their antioxidant activity was evaluated by DPPH test. The best antioxidant agent resulted the (3,4-dihydroxyphenyl) ethyl-α-D-glucopyranoside; it showed a radical scavenging activity similar to that of the hydroxytyrosol, together with an increased hydrosolubility. This molecule could be a good response to many food industry demands, always in search of cheap antioxidants with nutritional properties to improve the nutritional value and the quality of foods.