The invention discloses an extremely-heat-resistant beta-
mannosidase gene as well as an
expression protein and an application thereof, wherein the
DNA (deoxyribonucleic acid) sequence of the extremely-heat-resistant beta-
mannosidase gene is as shown in SEQ NO: 1, and the
amino acid sequence of the extremely-heat-resistant beta-
mannosidase expressed by the extremely-heat-resistant beta-mannosidase
gene is as shown in SEQ NO: 2. The extremely-heat-resistant beta-mannosidase has extremely strong heat-resistant performance and the characteristic of
high activity in a
neutral pH condition, and the enzymatic activity is the highest and the
specific enzyme activity achieves 144.6 U / mg in the conditions of 85 DEG C and a pH of 5.5; and the
protease has a high
enzyme activity at a temperature
ranging from 70 to 95 DEG C and a pH
ranging from 5.0 to 7.5. The mannosidase is extremely high in heat-resistant performance, and the residual
enzyme activity is about 70% in the case that the mannosidase is heat-insulated for 2h at 80 DEG C. Via the characteristics aforementioned, the mannosidase expressed by the extremely-heat-resistant beta-mannosidase gene disclosed by the invention has more advantages than the existing mannosidase, is suitable for degradation for
hemicellulose in the conditions of a high temperature of greater than 80 DEG C and a slightly acidic pH, and has a potential industrial application value.