[Screening of acidic xylanase producing strain and studies on its enzyme production conditions]

From 150 fungal strains, the authors found 8 strains contained mainly of xylanase activity over 100 U/mL in which the No. 149 strain was the highest xylanase producer. Which tentatively identified as Aspergillas niger. The appropriate medium composition was as follows: wheat bran hemicellulose 4%; NaNO3 1%; wheat bran 1% prepared in Mandels nutritional solution without (NH4)2SO4 and urea. After cultivated in shake-flask at 28 degrees C-32 degrees C for 60 h, the activity reached the highest value of 357.2 U/mL. The optimum pH of xylanase was 4.6 and it was stable at pH3-11. The fermented broth of strain 149 contained in addition to xylanase (relative activity 100) also included amylase(1.8), mannanase(0.98), beta-xylosidase(0.94) and cellulase(0.17).