Xylanase has specific activity to cleave the 1,4-β-D-xylosidic linkages in xylan, and is widely used in the feed, paper making, textile, food and chemical industries. To increase the degradation of cellulose in feedstuff and improve the absorption of nutrient, xylanase is generally supplemented in the animal feed which main ingredients contain more cellulose and semicellulose. Due to the thermolability under high-temperature feed processing, application efficacy of xylanase is much limited.

Currently, industrialized xylanases are mainly from microorganisms (bacteria and fungi), which is thermolability and complex processing. Dr. Yao Bin and his research team of the Feed Research Institute of CAAS focused on the study of xylanases. They identified four key amino acid residues related to the thermostability of a xylanase from Streptomyces sp. S9 (XynAS9) and constructed five mutants by using multiple sequence alignment, molecular dynamic simulation, site-directed mutagenesis approaches. In comparison to wild type XynAS9, the mutants had a temperature optimum of 2-17°C higher and better thermostability at 70^°C (increased by 1-10 fold). The thermophilic mechanism of these mutants were also stuided. This study not only reveals the thermophilic mechanism, but also provides a good material for research and industrial applications.

Results of this study have been published in Applied and Environmental Microbiology (IF 3.952, http://aem.asm.org/content/early/2014/01/20/AEM.03458-13 ).