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. ASh 4 ‎ , Bacillus sp. AGh 1 ‎ and ‎Bacillus sp. AG 2 ‎ with ‎ 90 ‎%, ‎ 77 ‎% and ‎ 45 ‎% residual activity at pH=‎ 4 ‎ and ‎ 60 oC after three ‎hours. Molecular identification of the bacteria was carried out using ‎ 16 S 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 ‎.‎

Keywords:

Cellulase , Thermostability , Hot spring , Acidostability