NOVELTY - A recombinant polypeptide comprises a fully defined 4 amino acids motif (SEQ ID NO: 9) and a fully defined 5 amino acids motif (SEQ ID NO: 10) where the polypeptide has lactonase activity, is new.    USE - The recombinant polypeptide is useful for producing aldonic acid and a composition, and where the composition and methods are useful for degrading biomass; for deconstructing biomass; for food processing; for producing a food additive; for textile cleaning; and for paper pulp bleaching (all claimed).    ADVANTAGE - The recombinant polypeptide has conserved motifs and lactonase activity, such as Sporotrichum thermophile aldonolactonase 1, variants, and fragments.    DETAILED DESCRIPTION - A recombinant polypeptide comprises a Gly-Pro-Arg-His motif (SEQ ID NO: 9) and an Asp-Pro-Thr-Gx-Phe/Tyr motif (SEQ ID NO: 10) where the polypeptide has lactonase activity, is new. INDEPENDENT CLAIMS are:    (1) a composition comprising the recombinant polypeptide;    (2) an expression vector comprising a polynucleotide sequence encoding the polypeptide operably linked to a regulatory sequence;    (3) a host cell comprising the expression vector;    (4) a method of producing the recombinant polypeptide;    (5) a method of producing aldonic acid comprising contacting a hexose- delta -lactone substrate with a recombinant polypeptide comprising the Gly-Pro-Arg-His motif (SEQ ID NO: 9) and the Asp-Pro-Thr-Gx-Phe/Tyr motif (SEQ ID NO: 10) where the polypeptide has lactonase activity;    (6) a method of degrading biomass comprising contacting the biomass with the composition;    (7) a method of deconstructing biomass comprising contacting biomass with the composition to thus deconstruct the biomass;    (8) a method of food processing comprising contacting a plant material with the composition to yield digestible plant material;    (9) a food additive comprising the composition;    (10) a method of textile cleaning comprising contacting a soiled textile with the composition to yield clean textile; and    (11) a method of paper pulp bleaching comprising contacting paper pulp with the composition to yield bleached paper pulp.