The screening and selection of trichoderma species capable of Producing extracellular cellulolytic enzymes from soil of Decaying plant materials

Abstract

The study of the screening and selection of Trichoderma species capable of producing extracellular cellulolytic enzymes from soil of decaying plant materials and investigation of the optimum conditions for their production of the enzymes was undertaken in order to obtain organisms with cellulolytic capability. The soil samples were collected using sealed cellophane bags and a sterile spatula by digging twenty centimetres deep from the soil surface and fungal isolation was carried out immediately. Isolation and identification of fungal isolates were performed using standard procedures and then screened for cellulase production. Optimization studies of enzymes production for selected Trichoderma species were conducted. Five Trichoderma species were isolated from the soil samples viz: Trichoderma koningii, T. reesei, T. longibrachiatum, T. harzianum and T. viride. Three out of the five Trichoderma species isolated namely Trichoderma longibrachiatum, T. harzianum and T. viride produced appreciable amount of cellulase activity and were used for further studies. Maximum production of cellulase was obtained on the 11^th day in all isolates. Commercial carboxymethyl cellulose (CMC) was the best substrate for cellulase production for all the isolated Trichoderma species giving the highest values of 786.67 reducing sugar equivalent per minute per millilitre of enzyme (units/ml) for T. longibrachiatum while potassium nitrate (KNO ₃₎ was the bestnitrogen compound for cellulase production with T. viride giving the highest value of 846.67 units/ml. Optimum production of cellulase was attained at a concentration of 10 mg/ml for carboxymethyl cellulose and 1.0 mg/ml for KNO₃ for all the three Trichoderma species. The study concluded that T. longibrachiatum, T. harzianum and T. viride isolated from soil of decaying plant materials produced proteins, which exhibited appreciable cellulase activity and could be used in producing cellulases for industrial and biotechnological uses.

Keywords: Cellulolytic enzyme; Trichoderma species; Soil samples; Industrial purposes; Optimum production.