Xylanase is an enzyme that has the highest prospects in the industry. Xylanase enzyme plays an important role, especially in the pulp industry, food and beverage as well as the production of xylose. Production of xylanase enzyme for industrial extraction of various types of living creatures including microorganisms. One of the microorganisms that produce xylanase enzyme is thermophilic bacteria. Enzyme generated from these bacteria are thermostable indispensable in the industrialized world. Mudiak Sapan Hot Springs of South Solok with temperatures at 93°C and pH 8 potentially contain a thermophilic bacterium that can produce xylanase enzyme. This study aims to determine the genus of thermophilic bacteria and determine the stability of the enzyme xylanase produced. Xylanase activity used Bailey modified methode and protein value used Lowry method. The result showed the genus Bacillus sp. on biochemical testing. Fifth isolates were classified into four isolates of Bacillus sp, including MS11 (Bacillus sp.1), MS12 and MS15 (Bacillus sp.2), MS16 (Bacillus sp.3) and MS18 (Bacillus sp.4), the five isolates xylanase enzyme that is stable, and isolates the most stable MS18 (Bacillus sp.4).
