Abstract
This study will evaluate Thermoactinomyces vulgaris HSB4 (KR698305) thermophilic microbial isolate for production of thermostable xylanase isolated from water spring in Aljouf, Saudi Arabia. Culture parameters for xylanase production by T vulgaris were optimized. The enzyme was concentrated by spinning through a centriplus, centrifugal ultrafiltration Millipore membrane with a total yield of 25%. The relative molecular mass of this xylanase determined by SDS-PAGE was ranging from 67-43 KDa. This extracellular xylanase therefore could be defined as thermostable with distinct properties that make the enzyme applicable for different industrial purposes.