Authors: sahar El-Nahrawy; M. Metwally; Rizk Y. Abd El-Kodoos; El-Sayed B. Belal; Samia A. Shabana; Ilham M. El-Refai
Twenty isolates of cellulase producing fungi were isolated from six samples of rotted rice straw which collected from different localities in El-Gharbia Governorate (Basyion), Kafrelsheikh Governorate (Sakha) and El-Dakahlia Governorate (El-Mansoura). On the basis of hydrolysis zone surrounding the colonies, an efficient fungus isolate (F7) for highest cellulolytic activity were chosen. According to morphological and biochemical characteristics as well as 18S rRNA sequence indicated that the isolate belonged to Aspergillus tubingensis KY615746.
Effect of culture conditions for production of cellulase enzyme by A. tubingensis were investigated under Submerged Fermentation (SMF) and Solid State Fermentation (SSF) techniques.
The optimum conditions for cellulase production by A. tubingensis were the best inoculum size was found to be 3%, pH 4, temperature 30 °C and incubation period 6th day where the reducing sugars attained (0.675, 0.728, 0.731 and 0.913 mg ml-1) with maximum activity (0.050, 0.055, 0.053 and 0.063 U ml-1 min-1), respectively for SMF conditions.
On the other hand, the maximum cellulase activity under SSF technique with moisture level 10g : 30ml were (0.16 Ug-1min-1), incubation period 9th day, inoculum size 4 ml:10g, pH 5 and temperature 30 °C where the reducing sugars were (1.412, 1.532, 1.551 and 1.521 mg g-1) with maximum activity (0.20, 0.22, 0.23 and 0.23 Ug-1min-1), respectively .
Based on the results, it may be concluded that rice straw waste can be a potential substrate for produce cellulase by SSF technique.