Isolation and Identification of New Cellulases Producing Thermophilic Bacteria from an Egyptian Hot Spring and Some Properties of the Crude Enzyme

Abstract

Thermophilic cellulases producing bacteria have been isolated from an Egyptian hot spring by enrichment of the water and soil samples with cellulose for 3 weeks at 70 C. Three isolates termed EHP1, EHP2 and EHP3 have been isolated. The phylogenetic analysis of these strains using its 16S rDNA sequence data showed that strain EFP1 had highest homology (98.5%) with Anoxybacillus flavithermus, EFP2 showed 98.5 % similarity with Geobacillus thermodenitrificans and EHP3 showed 99.0 % similarities with Geobacillus stearothermophilus. Maximal cellulases production by Anoxybacillus flavithermus EHP2 was detected at the end of the stationary phase (36 h). The crude cellulase had activity toward avicell, CMC, cellobiose, and xylan, but there was no detectable activity on p-nitrophenyl-â-d-glucopyranoside. The rate of CMC degradation was higher than any other substrates used in this study. The optimum temperature and pH for the crude enzyme activity was 75 C and 7.5, respectively.