The water-insoluble part of Parachlorella kessleri HY1 biomass was subjected to the extraction of cell-wall polysaccharides using polar aprotic solvents (DMSO, LiCl/DMSO) and aqueous alkaline solutions (0.1, 1 and 4 mol·l-1 of NaOH). Proteins predominated in all the crude extracts and in the insoluble residues were partially removed by treatment with proteolytic enzymes (pepsin and pronase), and in some cases with the HCl/H2O2 reagent, yielding purified polysaccharide-enriched fractions. These treatments led to the solubilisation of some products in water. The composition and structure of isolated polysaccharides were characterised based on monosaccharide composition, glycosidic linkage and spectroscopic analyses. The DMSO extract contained mainly proteins, and polysaccharides were not detected. The water-soluble parts isolated from the LiCl/DMSO extract contained α-l-rhamnan, α-d-glucan and β-d-glucogalactan; the water-insoluble part contained (1 → 4)-β-d-xylan, first isolated from the biomass of green microalgae. The alkali extracts contained polysaccharides of similar structure, and also water-insoluble (1 → 4)-β-d-mannan. The insoluble part after all extractions contained α-chitin as the main polysaccharide, which was confirmed by spectroscopic methods. All these polysaccharides can play a certain role in the cell wall structure of this microalga.

Department of Biochemistry and Microbiology Faculty of Food and Biochemical Technology University of Chemistry and Technology Prague Technická 5 166 28 Prague 6 Dejvice Czech Republic

Department of Biotechnology Faculty of Food and Biochemical Technology University of Chemistry and Technology Prague Technická 5 166 28 Prague 6 Dejvice Czech Republic; EcoFuel Laboratories s r o Ocelářská 9 Prague 9 Libeň 190 00 Czech Republic

Department of Carbohydrates and Cereals Faculty of Food and Biochemical Technology University of Chemistry and Technology Prague Czech Republic

Institute of Microbiology Czech Academy of Sciences Centre Algatech Novohradská 237 Opatovický mlýn 379 81 Třebon Czech Republic

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