Strain and Culture Conditions

P. janthinellum XAF01 was isolated from soil samples collected from Honghe, Yunnan province, China. For the production of xylanase, P. janthinellum XAF01 was cultivated in 250 ml Erlenmeyer flasks containing 60 g/L corncob as carbon source in 50 ml minimal medium (0.2% NaNO₃, 0.6% KH₂PO₄, 0.05% MgSO₄⋅7H₂O, 0.15% K₂HPO₄) supplemented with 0.3% yeast extract and 1.0% beef peptone. Under a condition of pH 3.5, temperature at 25°C and lasting for 7 days, cultures grew with shaking at 125 r/min. After growth, the culture supernatant was separated from the mycelium by centrifugation at 10,000 r/min for 20 min. The supernatant solutions, hereafter called crude extracts, were stored at 4°C for subsequent use.