Isolation of thermotolerant Isoptericola variabilis IDAH9 and optimization of its exoglucananse activity

This study aimed to isolate the thermophilic bacteria producing exoglucanase from hot springs of Dehloran, in Ilam province, in South-West of Iran. After sampling, bacterial enrichment was performed in a medium containing rice barn or CMC (carboxymethyl cellulose). Identifying bacteria was performed based on characteristics such as universal 16SrRNA gene sequencing using PCR. The isolates indicated the most similarity to species Pseudoxanthomonas mexicana¡ Chelatococcus daeguensis,Promicromonospora sp., Isoptericola variabilis sp. in the GenBank. The selected strain was identified and named as Isoptericola variabilis sp. IDAH9. The strain showed 1 U/ml exoglucanas activity. In order to optimization of enzyme production, the effects of carbon, nitrogen, Tween-80, and sucrose were evaluated. The results showed that the most exoglucanas activity are obtained at concentrations of 0.2% sucrose, 0.6% Tween 80 and 12 g/l of bran and carboxymethyl cellulose carbon sources and 5.6 g/l of ammonium sulfate. The residual enzyme activity was retained 64% of activity after 24 hour incubation at 50 °C. Therefore, Isoptericola variabilis sp. IDAH9 can be a suitable option for production thermostable exoglucanase from low price carbon sources.