Isolement et caractérisation de souches fongiques de milieux extremes (sol et sebkha de la région de Biskra) productrices de cellulase themostable à interet industriel

Abstract

The microscopic study of the moulds isolated from Sebkhas of Biskra area allowed, to identify 7 different kinds from 10 potentially cellulolytic strains: Aspergillus, Penicillium, Geotrichum, Altarnaria, Cladosporium, Altarnaria and Trichoderma. The fermentation of the 10 strains selected and cultivated on a medium containing date scrap (under product of pheonicical industry) as a substrate of fermentation, allowed to select hypercellulolytic strains with a cellulasic activity of 775 U. The strain (R3), isolated from the ground soil of palm plantations of Biskra corresponds to the Trichoderma kind. This train is retained for the kinetic study of the biomass, the cellulasic activity, sugar, proteins like that of the pH. This study reveals that the synthesis of the enzyme reaches its maximum after 60 hours of fermentation during the stationary phase of the growth. A partial purification with ammonia sulphate 40 % of saturetion reduced the content of proteins of 78.4 % and increased the specific activity to 94.35 % which reached the degree of purification to 17.70. The enzyme was found very thermostable with a half-life of 170 , 140, 120 and 50 munites at 60, 70, 80 and 90°C respectively. The corresponding temperature for the maximum cellulolytic activity was 55°C whereas the optimim pH was 4.8.