Fig. 5

3D surface plot showing the interaction between significant factors affecting xylanase production. a Substrate concentration and yeast extract. b Substrate concentration and MgSO4. 7H2O. c Substrate concentration and KH2PO4. d (NH4)2SO4 and KH2PO4. e (NH4)2SO4 and MgSO4. 7H2O. f KH2PO4 and MgSO4. 7H2O