Samudra Prosad Banik, Swapan Bhattacharyya, Shakuntala Ghorai
Microbiology of Microbiology
A new strain of Penicillium chrysogenum producing a low Km, thermostable cellobiase was isolated from agricultural soil of rural West Bengal, India. The culture filtrate showed strong antibacterial activity against gram positive organisms, gave two cellobiase activity bands on native PAGE zymography and two peaks on sephacryl S200 gel chromatography. The higher molecular weight peak had a higher specific activity and was characterised further. It gave three bands corresponding to 130 kDa, 65 kDa and 55 kDa in SDS-PAGE and showed a Km of 0.196 mM against p- nitrophenyl β-D glucopyranoside. It was highly thermostable and retained full activity after one hour incubation at 55°C with temperature optima of 75°C. Its pH stability ranged between 4.5 and 8.5 with optimal activity at pH 5 and it retained more than 65% activity in presence of 100 mM guanidium hydrochloride and 2 M urea. Apart from Zn+2 and Hg+2, enzyme activity was not affected by other metal ions and in presence of Mg+2 and Mn+2, activity was boosted. It also retained more than 80% activity in presence of 0.5% glucose. This is one of the very few reports of an efficient cellobiase from the Penicillium genus which can be utilised for biotechnological applications.