Isolation of feed additive cellulase producing thermophilic Bacillus strains and partial characterization of the enzymes

In the present study, three thermophilic Bacillus strains were isolated from the soil samples collected from the Haruniye Thermal Spring located in Düziçi. The isolates were entitled as Bacillus sp. HR-1, HR-2, and HR-3, respectively. The maximum productions of cellulases were revealed at 72nd hour of incubation period for HR-1 and HR-2 strains, and at 24th hour of incubation period for HR-3 strain, respectively. The optimum enzyme activity was observed at 70 °C for HR-3 cellulase, whereas at 60 °C for HR-1 and HR-2 cellulases. On the other hand, optimum pH value for HR-2 cellulase was 4.0, whereas 5.0 for HR-1 and HR-3 cellulases. All enzymes protected their activities after pre-incubation at 60 °C for 30 min, but they begin to decrease after pre-incubation at higher temperature values. The specific activities of HR-1, HR-2, and HR-3 bacterial cellulases were 34.1, 67.8 and 112.3 U/mg at 55 °C, respectively.