Regulation of Endo- ß-D- Xylanase and ß- Xylosidase Synthesis in Humicola lanuginosa

Humicola lanuginosa produced endo-ß-xylanase and ß-xylosidase when grown on different monosaccharides, disaccharides, commercial cellulose, cellulosic residues, xylan, and carboxymethyl cellulose (CMC) in shaken cultures. Among mono-saccharides, only xylose induced the cells to produce both enzymes. The organism synthesized endo-xylanase and ß-xylosidase maximally on xylan followed by wheat bran. Among nitrogen sources, corn steep liquor (CSL) supported the highest yields of endo-ß-xylanase and ß-xylosidase (1200 and 250 IU g-1 substrate respectively), which were 1.6- and 3.5-fold enhancement over the activities achieved on basal Vogel’s medium. In the presence of CSL, even mono-saccharides acted as inducers of both enzymes. This implied that synthesis of enzymes was regulated by both substrate and nitrogen sources. Additional of vitamin mixture did not enhance enzymes production. Optimal production of enzymes was observed over a temperature range of 45-50°C. These studies revealed that the thermophilic mould required less activation energy, enthalpy and entropy of activation for endogenous metabolism during growth and product formation compared with those of mesophilic and thermo-tolerant organisms reported in literature.