Production of Cold-Active Xylanase by Novel Trunctella angustata (BPF5) Strain Under Solid State Fermentation with Wheat Bran, Rice Bran and Saw Dust as Substrates

Abstract

Agro-industrial wastes are the most abundant renewable resources on earth, affordable and easily available in large quantities. Recently cold-xylanase which plays an important role in breakdown of xylan, has achieved a great attention due to its remarkable biotechnological applications. The aim of this study was to screen three filamentous fungi, Penicillium canesence (BPF4), Truncatella angustata (BPF5), and Pseudogymnoascus roseus (BPF6) available as laboratory stocks for their ability to produce extracellular xylanases at cold temperature. T. angustata was found predominant to produce the highest amount of xylanase followed by Pseu. roseus and P. canesence in that order and was selected for further studies. Under solid state fermentation, a comparative study of three substrates, wheat bran, rice bran and saw dust was investigated. Xylanase was maximally produced at 30^oC and pH 9. At 30°C and in presence of substrate wheat bran an enzyme activity 0.22/1/7.6=1.672 IU/ml was obtained which was far better that rice bran and saw dust. Effect of carbon source, nitrogen source, metal ions and surfactants were also observed and fungus showed remarkable production in presence of carbon source xylose followed by CMC both in presence of solid substrate wheat bran and saw dust. Most suitable nitrogen source was ammonium nitrate followed by yeast extract. All the optimized parameters (substrate- wheat bran, carbon source-xylose, nitrogen source-NH₄NO₃, temperature-30°C, pH-9) were added and comparative studies for xylanase production were made against basal SSF medium. With this integration of selected cultural and nutritional parameters an enzyme activity of 0.22/1/8.2= 19.4 IU/ml was obtained. All the metal ions and surfactants tested were found to inhibit enzyme yield by the fungus. The enzyme was also tested for some of the applications including biomass conversion and immobilization which showed wonderful results. Activity of xylanase production was confirmed by measuring the amount of reducing sugars liberated from the medium by the DNS method using crude extract. Xylanases production from T. angustata has thus been studied under various conditions in SSF and as a result an optimized production strategy has been achieved. Also, this is the first report of the fungus T. angustata having cold-active xylanases producing ability