Xylan is a primary constituent of the plant cell wall. As the second most abundant renewable polysaccharide in nature, after cellulose, xylan accounts for approximately one-third of the total renewable organic carbon on Earth. Monogastric animals, such as poultry, lack the endogenous ability to synthesize the enzymes necessary for xylan hydrolysis. This deficiency in hydrolyzing enzymes leads to incomplete digestion and inefficient absorption of nutrients in these animals. Xylan encases other nutrients, creating a 'cage effect' that entraps them within their kernels, thereby acting as a barrier to nutrient digestion in the small intestine. The adverse effects of xylan on feed have pro‎mp‎ted the use of xylanases in the hydrolysis of xylan-containing feed. Xylanases are glycosidases that catalyze the endohydrolysis of β-D-xylosidic-4,1 linkages in xylan. The primary sources of these enzymes are fungi and bacteria, which are widely employed in the industrial production of xylanase. Consequently, identifying productive strains with high potential for xylanase production, as well as obtaining an enzyme with favorable temperature and pH characteristics, has been a priority to reduce enzyme production costs and create a suitable platform for strain and enzyme engineering. Therefore, the identification of superior productive strains for engineering purposes has been a key objective. In this study, two bacterial strains were isolated from 26 samples prepared from the soil of the Goukhoni swamp and the Kashan desert, which demonstrated the ability to hydrolyze xylan. Based on the standard curve of D-xylose and the maximum average absorbance measured, the concentration of the produced enzyme was estimated to be 33,340 and 34,480 units per gram for the S3 and S4 strains, respectively. The produced xylanase enzyme was separated using an anion chromatography column, and its molecular mass was estimated to be 23 kDa based on SDS-PAGE gel analysis. The S3 and S4 strains were identified as belonging to the Bacillus subtilis genus and species based on 16S rRNA and rpoB gene sequences. An examination of the stability results of the produced enzyme revealed that the S4 strain is more effective at high temperatures than the S3 strain. Therefore, if temperature tolerance is required, the use of the S4 xylanase enzyme is recommended. Additionally, the data showed that strain S3 maintains its performance over a wider range of pH values.

ابوذر سورني

محمد صدقي

مجيد طالبي , صادق زارعي