Production and in vitro evaluation of oligosaccharides generated from lichenan using immobilized Penicillium occitanis lichenase

• Immobilized P. occitanis lichenase exhibited better thermal and pH stability than the free one.
• Immobilization provides a facile method for the production of oligosaccharides.
• Generated oligosaccharides have an antioxidant and antibacterial activity.

Lichenase from Penicillium occitanis Pol6 was immobilized on glutaraldehyde crosslinked chitosan–clay composite beads and used for lichenan hydrolysis. The immobilization yield and lichenase activity were 94.81 ± 4.7% and 72.17 ± 3.6% of initial activity, respectively. Optimum pH of the free and immobilized Lic-Pol6 was found to be between 3.0 and 4.0. Immobilized Lic-Pol6 was more active and retained more than 94% of its relative activity in the range of 40–80 °C. The immobilized Lic-Pol6 retained 63.7% of its activity after eight cycles of uses. It also exhibited high storage stability and had only 37% activity loses after 120 days at 4 °C. The generated oligosaccharides GG showed a high antioxidative capacity (175 μmol/ml α-tocopherol equivalents) at 10 mg/ml and an important DPPH radical-scavenging activity (IC50 = 2.5 ± 0.01 mg/ml). Furthermore, GG had a high antimicrobial activity against Escherichia coli, Bacillus subtilis, Klebsiella pneumonia and Salmonella thyphimirium.

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