چکیده انگلیسی:
Cellulases with capability to have enzymatic functions at low pH and high temperature are important and include considerable portion of industrial enzymes. Endo-1,4-β-glucanase is one of the three cellulolytic enzymes in a triplet catalytic system that required for extracellular cellulose hydrolysis. In this study, the sampling was performed from four hot springs in north and northwest of Iran and the screening and identification of acid-stable and thermostable of endo-1,4-β-glucanase producing bacteria were investigated. Endo-1,4-β-glucanase of the isolated strains were determined by qualitative Congo-Red staining as well as quantitative Carboxymethylcellulose/Dinitrosalicylic acid methods as indicators of cellulase activity. Three isolates out of twelve initially selected bacteria, showed noticeable endo-1,4-β-glucanase activity, including Paenibacillus sp. ASh4 , Bacillus sp. AGh1 and Bacillus sp. AG2 with 90%, 77% and 45% residual activity at pH=4 and 60oC after three hours. Molecular identification of the bacteria was carried out using 16S rDNA partial sequencing, in which two isolates belonged to Bacillus sp. and one to Paenibacillus sp.. The results shown that the isolated acido-thermotolerant Bacillus spp. and Paenibacillus sp. had the capability to produce proper acid-stable and thermostable endoglucanase. These isolate also may be even considering as candidates for satisfactory production for other thermostable metabolites with further biotechnological applications.
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