NOVELTY - A modified beta -mannanase derived from the wild-type Trichoderma reesei mannanase of SEQ ID NO. 1 by insertion, deletion, and/or substitution of at least one amino acid residue of the wild-type mannanase and has one or more of the following enhanced phenotypes relative to the wild-type mannanase: increased thermostability, increased proteolytic stability, increased specific activity, and improved stability at low pH, or its variants, modified forms, homologs, fusion proteins, functional equivalents, or fragments, is new.    USE - The modified mannanase is useful for food and feed processing; for coffee extraction; for processing of coffee waste; as a supplement to food and feed; for enzyme aided bleaching of paper pulps; as bleaching and/or desizing agent in textile industry; for oil and gas well stimulation by hydraulic fracturing; as detergent; for removal of biofilms; in delivery systems; and/or for the processing of renewable resources intended for the production of biological fuels (claimed).    ADVANTAGE - The modified beta -mannanase has enhanced phenotypes relative to the wild-type mannanase, including increased thermostability, increased proteolytic stability, increased specific activity, and improved stability at low pH (claimed).    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are:    (1) a nucleic acid molecule selected from: (a) a nucleic acid molecule encoding the modified mannanase, preferably a mannanase having an amino acid sequence of SEQ ID NO. 10 (variant B), SEQ ID NO. 11 (variant C), SEQ ID NO. 12 (variant 31), or SEQ ID NO. 13 (variant 16); (b) a nucleic acid molecule encoding for a derivative of the modified mannanase, in which one or more amino acid residues are conservatively substituted; (c) the nucleic acid molecule of SEQ ID NO. 2; (d) a nucleic acid molecule that is a fraction, variant, homologue, derivative, or fragment of the nucleic acid molecule of SEQ ID NO. 2; (e) a nucleic acid molecule that is capable of hybridizing to any of the nucleic acid molecules of (a)-(d) under stringent conditions; (f) a nucleic acid molecule that is capable of hybridizing to the complement of any of the nucleic acid molecules of (a)-(d) under stringent conditions; (g) a nucleic acid molecule having a sequence identity of at least 70-95% with any of the nucleic acid molecules of (a)-(f) and encoding for a mannanase; or (h) or a complement of any of the nucleic acid molecules of (a)-(g);    (2) a vector comprising the nucleic acid molecule;    (3) a host cell transformed with the vector and/or comprising the nucleic acid molecule; and    (4) a method for preparing the modified mannanase.