NOVELTY - An isolated protein comprising a 330 amino acid sequence (SEQ ID NO: 31) fully defined in the specification, is new.    USE - The protein having endo- beta -mannanase activity produced by nucleic acid, expression vector and host cell is useful for preparing composition for producing fuel, converting biomass comprising a plant material chosen from Miscanthus, switchgrass, cord grass, rye grass, reed canary grass, common reed, wheat straw, barley straw, canola straw, oat straw, corn stover, soybean stover, oat hulls, Sorghum, rice hulls, sugarcane bagasse, corn fiber, distillers dried grains with solubles (DDGS), bluestem, corncobs, pine, willow, aspen, poplar wood and energy cane into sugars, processing food by contacting the composition with plant material chosen from palm kernel, coconut, konjak, locust bean gum, gum guar, soybeans, barley, oats, flax, wheat, corn, linseed, citrus pulp, cottonseed, groundnut, rapeseed, sunflower, peas and lupines, cleaning textiles and bleaching paper pulps (all claimed) e.g. chemical pulps, semi-chemical pulps, kraft pulps, mechanical pulps, pulps prepared by the sulfite method and chlorine free pulps bleached with oxygen, ozone, peroxide or peroxyacids and in enzyme aided bleaching of pulps produced by modified or continuous pulping methods that exhibit low lignin contents. The sugars are monosaccharides, disaccharides and oligosaccharides which are used as chemical or fermentation feedstocks from biomass for the production of ethanol, other products or intermediates. The sugars further include mannose and mannopolymers such as mannobiose, mannotriose, mannotetraose, mannopentaose, and/or mannohexaose by contacting the protein with polymannose-containing material. The protein is used in combination with other carbohydrases (e.g. glucanase, xylanase, alpha-galactosidase and/or cellulase) for more extensive hydrolysis of the plant material. Can also be used as feed additives for monogastric animals e.g. poultry and swine, food additive and feed pretreatment agent, in producing and/or processing food or animal feed, and in detergent compositions in the form of e.g. bar, tablet, powder and paste to facilitate the removal of mannopolymer containing stains or soils in combination with other enzymes e.g. amylases, cellulases, lipases, pectinases, proteases and endoglucanases.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) composition comprising the above-mentioned isolated protein;    (2) isolated nucleic acid capable of encoding endo- beta -mannanase comprising a 330 amino acid sequence (SEQ ID NO: 31) fully defined in the specification;    (3) expression vector comprising the isolated nucleic acid operably linked to a regulatory sequence;    (4) host cell comprising the expression vector; and    (5) method of preparing fuel involves contacting biomass with the composition to yield a sugar solution and culturing the sugar solution with a fermentative microorganism under suitable conditions.