NOVELTY - An Isolated polypeptide (I) comprising 2,6-beta-D-fructan hydrolase (FH) activity, is new.    USE - The new protein is used for the following: (1) to remove microbial biofilm from surfaces, particularly for reduction of biocorrosion, for treatment of dental plaque and for treatment of multiple sclerosis (eliminating biofilm from the lungs); (2) to hydrolyze slime; (3) in detergents; and (4) for production of fructose oligomers from levan or phlein (useful as sweeteners or for conversion to fructose). Nucleic acid that encode (I) are used for recombinant (I) production and as source of probes and primers for identification and cloning of related fructan hydrolases (all claimed).    DETAILED DESCRIPTION - (I) may be one of the following polypeptides:    (a) a polypeptide that has at least 55.3% identity with amino acids (aa) 32-923 of a 923 aa sequence (A), aa 25-1277 of a 1277 aa sequence (B) or aa 29-943 of a 943 aa sequence (C) (representing mature polypeptides);    (b) a polypeptide encoded by a nucleic acid that hybridizes under low stringency conditions with nucleotides (nt) 94-2769 of a 2769 base pair (bp) sequence (D), 73-3824 of a 3834 bp sequence (E) or 85-2832 of a 2832 bp sequence (F), cDNA comprising these regions, their subsegments of at least 100 nt or the complements of any of them;    (c) a polypeptide that is an (allelic) variant of (A), (B) or (C) with one or more aa substitutions, deletions and/or insertions;    (d) a fragment of (a)-(c) that has FH activity; or    (e) a polypeptide that has optimum FH activity at pH 3.5-9.5 at between 20-70degreesC (especially 37degreesC) and a molecular weight of at least 88 kD.    INDEPENDENT CLAIMS are also included for the following:    (1) a nucleic acid (II) that encodes (I);    (2) a nucleic acid produced by:    (a) hybridizing a DNA with nucleotides as defined above in (b), the cDNA sequence comprised in these nucleotides, a subsequence of the cDNA or the nucleotides or of at least 100 nucleotides (or any of their complements); and    (b) isolating the nucleic acid sequence;    (3) nucleic acid construct containing (II) linked to control sequences;    (4) recombinant expression vector or host cell containing this construct;    (5) production of mutant nucleic acid (IIa) by introducing at least one mutation into the region of (D), (E) or (F) that encodes the mature protein;    (6) (IIa) produced this way;    (7) producing (I) or its mutant forms by culturing suitable strains;    (8) composition containing (I) or (Ia);    (9) disintegrating microbial biofilm by treating with a polypeptide having endo-FH activity (or (I)) in aqueous medium in order to reduce bio-corrosion of a hard surface;    (10) process for hydrolyzing slime by treatment with (I) in aqueous medium; and    (11) production of 2,6-beta-D-fructose oligomers (III) by treating levan or phlein with (I) or (Ia), optionally followed by conversion of (III) to fructose by treatment with a 2,6-beta-D-fructan exo-hydrolase.