Isolation and Screening of Thermophilic Bacteria for Producing Cellulase Enzyme Using Agricultural Waste

Abstract

Wheat straw was used as a source for isolating thermophilic bacteria and as a substrate for cellulase production. Twenty five of thermophilic bacterial isolates were isolated from agricultural waste samples on Luria-Bertani (L.B) agar plates. These bacterial isolates were qualitatively tested at 50˚C for cellulose production by flooding plates containing mineral salts medium (MSM) with 2% of wheat straw and 0.5% Congo red dye for 15 min followed by repeating wash with 1M NaCl. Results showed that 12 isolates gave a clear zone, after Congo red dye staining of plates; this indicated that the colonies produce cellulase. Bacterial isolates were screened for enzyme activity in submerged liquid MSM with 2% of wheat straw at 50˚C. The produced enzyme is then examined for reducing sugar release in liquid medium. Results revealed that 2T5, 3T13 and 3T18 isolates were the highest in producing cellulase enzyme 5.9, 13.7 and 14.3 Unit/ml, respectively. The most active isolates 2T5, 3T13 and 3T18 were identified on the basis of morphological, biochemical characteristics and API identification kits, they were identified as Bacillus subtilis, Bacillus megaterium and Bacillus licheniformis, respectively.