Production of β-glucanase enzyme from Penicillium oxalicum and Penicillium citrinum

Abstract

Two Penicillium species namely, Penicillium oxalicum and Penicillium citrinum cultivated by solid surface fermentation method using rice bran homogenized with 0.5% (w/v) (NH₄)₂SO₄ solution as nitrogen source and Whatman no. 1 filter paper (WFP1) as substrate for β-glucanase enzyme production medium were found to show a dense growth. Studies on the enzyme, using soluble cellulose (SC) and methyl cellulose (MC) as cellulose-glucan source and Somogyi titrimetric method, revealed optimum temperature for enzyme activity from the Penicillium species, ranging from 50 to 55°C and thermostability of up to 70°C after 15 to 30 min incubation in sodium phosphate buffer. It was found that the metal ions (0.5 to 5.0 M) namely: Zn²⁺, Cu²⁺ and Hg²⁺ did not enhance β-glucanase activity. Cu²⁺ ions reduced the enzyme activity slightly, Zn²⁺ ions had no effect, while Hg²⁺ completely inhibited β-glucanase activity. β-Glucanase can be produced from some fungal species locally using the abundant agricultural wastes (such as rice bran) as substrates.

Key words: Fermentation, methylcellulose, metal inhibitors, soluble cellulose, Penicillium species.