Gene characterization, cloning and over-expression of two xylanases from Streptomyces padanus J103

Abstract

Xylan, a component of plant cell wall, is the most abundant non-cellulosic polysaccharide in nature. Xylanase can use to digest xylan that use for several industries such as bioethanol production, bio-bleaching of pulp, textile, production of animal feed. Streptomyces padanus strain J103 was isolated from Incheon area in Korea. Two xylanase genes (J103-x2, J103-x7) from S. padanus J103 was cloned and overexpressed in E. coli expression system. The recombinant enzymes were purified using ion-exchange chromatography with Ni+ charged column. J103-x2 and J103-x7 were 693 bp (230 aa) and 1011 bp (336 aa), separately. The J103-x2 showed the highest sequence identity of 78.4% to endo-1,4-beta-xylanase [Streptomyces sp. e14]. The J103-x7 showed the highest sequence identity of 67.1% to endo-1,4-beta-xylanase [Streptomyces sp. TN119]. Also, the molecular mass of xylanases was estimated to be 24 kDa and 35 kDa, separately. Both recombinant xylanases showed the highest activities at 60°C and pH 4.0. However their thermostability showed a significant difference. The J103-x2 was stable and retaining more than 90% of its activity after pre-incubation at 50°C for 120 min, whereas J103-x7 lost most of its activity after pre-incubation at 50°C for just 30 min.of animal feed. Streptomyces padanus strain J103 was isolated from Incheon area in Korea. Two xylanase genes (J103-x2, J103-x7) from S. padanus J103 was cloned and overexpressed in E. coli expression system. The recombinant enzymes were purified using ion-exchange chromatography with Ni+ charged column. J103-x2 and J103-x7 were 693 bp (230 aa) and 1011 bp (336 aa), separately. The J103-x2 showed the highest sequence identity of 78.4% to endo-1,4-beta-xylanase [Streptomyces sp. e14]. The J103-x7 showed the highest sequence identity of 67.1% to endo-1,4-beta-xylanase [Streptomyces sp. TN119]. Also, the molecular mass of xylanases was estimated to be 24 kDa and 35 kDa, separately. Both recombinant xylanases showed the highest activities at 60°C and pH 4.0. However their thermostability showed a significant difference. The J103-x2 was stable and retaining more than 90% of its activity after pre-incubation at 50°C for 120 min, whereas J103-x7 lost most of its activity after pre-incubation at 50°C for just 30 min.