Screening of bacteria producing acid-stable and thermostable endo‏-‏‏1,4‏‎-β-glucanase from hot springs of North and Northwest of Iran

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.‎