ABSTRACT
Marine algae are an important resource for food, feed, medicine, and industrial materials. They are also intriguing because they contain some peculiar polysaccharides, such as agar, alginic acid, carrageenan, fucoidan, and porphyran (Percival and McDowell1967) that are not included in the cell wall of terrestrial plants. ~-1,3-Xylan is one of those algal polysaccharides. Xylan can be divided into Ji-1,4-xylan and Jl-1,3-xylan on the basis of their structures. Jl-1,3-Xylan is generally a homopolymer of Jl-1,3-linked 0-xylose (Percival and McDowell 1967). Ji-1,4-Xylans are heterogeneous polysaccharides that have a Ji-1,4-linked 0-xylose backbone and are found with cellulose in the cell walls of all terrestrial plants (Horton and Wolfrom 1963, Whistler and Richards 1970). The hydrolysis of the main chain of Ji-1,4-xylan is achieved by Ji-1,4-xylanases (1,4-Ji-0xylan xylanohydrolase; EC 3.2.1.8) and Ji-xylosidases (1,4-Jl-D-xylan xylohydrolase; EC 3.2.1.37). The Ji-1,4-xylanases attack internal Ji-1,4xylosidic linkages on the backbone and form several xylooligosaccharides. The ~-xylosidases release xylosyl residues by exowise cleavage of xylooligosaccharides. Ji-1,4-xylanases are produced by many kinds of microorganisms, including aerobic and anaerobic mesophiles and thermophiles, and their biochemical and molecular characteristics have been widely studied because they have wide industrial applications (Biely 1985, Okazaki et al. 1985, Tan et al. 1987, Tsujibo et al. 1990, Viikari et al. 1994, Ohmiya et al. 1997, Mong et al. 1988, Kulkarni et al. 1999).
