Screening and Identification of Heat-Resistant Xylanase-Producing Strain and Investigation of Fermentation Conditions

In this research, we isolated a thermostable xylanase-producing strain FSD0302 from Jiuqu (a traditional Chinese liquor fermentation starter) from Zibo, Shandong, and we identified it as Thermomyces lanuginosus. The fermentation conditions for the production of xylanase by this strain were investigated by one-factor-at-a-time method. The results showed that a higher xylanase activity of 5 357.1 U/mL was obtained under the following conditions: particle size of corncob xylan 20-40 mesh, xylan concentration 4 g/100 mL, initial medium pH 6.0, fermentation temperature 50℃, and rotational speed 200 r/min, which was 3.9 times as much as that before the optimization. The specific activity was calculated as 10 493.72 U/mg. Strain FSD0302 produced two xylanases with different molecular masses of about 20 and 60 kDa, respectively. The enzymatic properties showed that the optimum temperature was 75℃ for both xylanases, and the optimum pH was 5.5 and 7.5, respectively. Over 50% of the xylanase activity could be retained in the pH range of 3.5-9.0. To sum up, the thermostable xylanase from T. lanuginosus FSD0302 is promising for application in the production of xylooligosaccharides. © 2019, China Food Publishing Company. All right reserved.