Abstract
In this study, two isolates (PSAU1 and PSAU2) of aerobic bacteria were isolated from the desert soil (harsh environment temperature of 45 degrees C) of Saudi Arabia. The bacteria were isolated and their isolates (PSAU1 and PSAU2) were characterized through PCR amplification and a sequencing approach targeting the 16S RNA genes. Based on the sequencing results of the PSAU1 and PSAU2 isolates, 99% of the sequence identity were matched with the Bacillaceae family belonging to Bacillus megaterium (PSAU1) and Bacillus cereus (PSAU2) species. The cellulolytic activities of both isolates (PSAU1 and PSAU2) at 45 degrees C (pH 7.0) were also performed in the presence of carboxymethyl cellulose (CMC) used as a carbon source. The colonies isolated from PSAU1 and PSAU2 were grown on CMC agar medium and observed for 5 days to recover the maximum inhibition i.e. cellulase production using plate assay methods. The PSAU1 colony gave negative signals i.e. non-cellulolytic (B. megaterium) whereas the PSAU2 (B. cereus) isolate showed a positive signal or zone of inhibition on CMC-agar plates at 45 degrees C.
Furthermore, cellulase activity was quantified in a CMC-supplemented medium and the maximum recovery of cellulases was 2.03 +/- 0.08 U/ml on 2 days of culture at 540 nm. Our observation indicates that desert soil is also a good source of cellulolytic microorganisms that can be useful for cellulose degradation in harsh environments (temperature > 40 degrees C). The fast growth of these isolates and cellulase activity are new contributions to the field of biotechnology, especially in the Arab region.