Abstract: The present invention relates to polypeptides having xylanase activity and catalytic domains and polynucleotides encoding the polypeptides and catalytic domains. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods of producing and using the polypeptides and catalytic domains.

Abstract: A new enzyme, alternanase, which is effective for the endo-hydrolytic cleavage of alternan, producing a thinned composition of low molecular weight fractions which exhibit reduced viscosity and increased solubility relative to native alternan, is described. The enzyme is produced and secreted extracellularly by a plurality of novel bacteria isolated from soil. One of the fractions present in the thinned alternan resulting from hydrolysis with alternanase is a the cyclic tetrasaccharide, cyclo{-6)-.alpha.-D-Glcp-(1,3)-.alpha.-D-Glcp-(1,6)-.alpha.-D-Glcp-(1,3)-. alpha.-D-Glcp-(1-}. A novel method for isolating strains of microorganisms which produce endo-.alpha.-D-glucanases such as alternanase effective for the endo-hydrolytic cleavage or thinning of alternan is also described. Cultures of the subject strains are contacted with a test substrate of alternan coupled to a detectable indicator. Detection of released indicator provides an indication of endo-.alpha.-D-glucanase activity.

Abstract: A new enzyme, alternanase, which is effective for the endo-hydrolytic cleavage of alternan, producing a thinned composition of low molecular weight fractions which exhibit reduced viscosity and increased solubility relative to native alternan, is described. The enzyme is produced and secreted extracellularly by a plurality of novel bacteria isolated from soil. One of the fractions present in the thinned alternan resulting from hydrolysis with alternanase is a the cyclic tetrasaccharide, cyclo{-6)-.alpha.-D-Glcp-(1,3)-.alpha.-D-Glcp-(1,6)-.alpha.-D-Glcp-(1,3)-. alpha.-D-Glcp-(1-}. A novel method for isolating strains of microorganisms which produce endo-.alpha.-D-glucanases such as alternanase effective for the endo-hydrolytic cleavage or thinning of alternan is also described. Cultures of the subject strains are contacted with a test substrate of alternan coupled to a detectable indicator. Detection of released indicator provides an indication of endo-.alpha.-D-glucanase activity.