Improvement of highly thermostable xylanases production by Talaromyces thermophilus for the agro-industrials residue hydrolysis.

A newly isolated thermophilic fungal strain from Tunisian soil samples was identified as Talaromyces thermophilus and was selected for its ability to produce extracellular hemicellulases when grown on various lignocellulosic substrates. Following the optimization of carbon source, nitrogen source, and initial pH of the growth medium in submerged liquid cultures, yields as high as 10.00 +/- 0.15 and 0.21 +/- 0.02 U/ml were obtained for xylanase and beta-xylosidase, respectively. In fact, wheat bran was found to be a good inducer of hemicellulase enzymes, mainly beta-xylosidase. The optimal temperature and pH of the xylanase activity were 75 degrees C and 8.0, respectively. This enzyme exhibited a remarkable stability and retained 100% of its original activity at 50 degrees C for 7 days at pH 7.0-8.0. The half-lives of the enzyme were 4 h at 80 degrees C, 2 h at 90 degrees C, and 1 h at 100 degrees C. T. thermophilus could therefore be considered as a satisfactory and promising producer of thermostable xylanases. Crude enzyme of T. thermophilus rich in xylanase and beta-xylosidase was established for the hydrolysis of lignocellulosic materials as wheat bran.