Abstract
This research was carried out to screen and characterize thermophilic bacteria that have the ability to produce cellulase enzyme. Bacterial strains were isolated from the sediment samples collected from Ras-Sedr's hot spring located in Ras-Sedr, Egypt. For cellulolytic activity testing, Carboxymethylcellulose (CMC) agar was used as growth medium. Seven bacterial isolates showed variable zones of CMC clearance. Evaluation of cellulase enzyme thermal activity was carried out at varying temperatures from 35°C to 85°C and the impact of pH on cellulase activity was evaluated at different pH levels of 5-9. Molecular identification for the isolates also conducted based on 16S rRNA gene sequencing. At 55°C and pH 7, all the seven bacterial isolates showed their optimum growth conditions. Strains were gram positive, have rod shape cells, spore forming and motile with the ability to produce thermostable cellulase. The results of the phylogenetic analysis reveal a high degree of sequence similarity between the isolated bacteria involved in this research and Geobacillus sp. These thermophiles have the ability to produce useful thermostable cellulase enzyme of industrial significance, which in turn indicates that Ras-Sedr's hot spring considered a prospective source of economically significant microorganisms which needs more studies through further researches.
Highlights
Since the development of the polymerase chain reaction, the enzymes of extreme thermophiles have been of significant concern in biotechnology [1]
Dinitrosalicylic acid) method by measuring the quantity of reducing sugar produced during hydrolysis [15].The optimum temperature for the activity of the crude cellulase enzyme was determined by incubating the enzyme separately at different temperatures ranging from 35°C to 85°C for 30 min
For the assessment of enzyme stability under various degrees of temperatures, the crude cellulase enzyme was kept for an hour separately at temperatures ranging from 35°C to 85°C for an hour and the optical density was measured at 540 nm
Summary
Since the development of the polymerase chain reaction, the enzymes of extreme thermophiles have been of significant concern in biotechnology [1] It is not surprising, given the usefulness of thermostable enzymes in molecular biological laboratory techniques, that they were suggested as strong resources for industrial catalysis [30]. Geothermal springs are often highly energetic environments because temperatures can reach the boiling point, and because their waters are often charged with elevated sulfur levels. They contain microorganism populations that may be a source of significant bioactive compounds such as thermostable enzymes [24]. Cellulase characterization based on pH and temperature was performed followed by molecular characterization of the isolates based on16s rRNA
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