MANGANESE PEROXIDASE (MnP) ACTIVITY OF SOME NIGERIAN EDIBLE MUSHROOMS

Abstract

Mushrooms are able to secrete manganese peroxidase (MnP), an important ligninolytic enzyme involved in degrading the highly abundant, complex and recalcitrant polymer, lignin. Ligninolytic enzymes produced by these mushrooms are essential for lignocellulosic waste degradation and detoxification in the environment. Few species especially from Nigeria have been screened for ligninolytic enzymes. Six species of the Nigerian edible mushroom were screened for manganese peroxidase (MnP) activity. Three different media, namely, Nutrient broth medium, minimal salt broth (MSB), medium supplemented with 10% crude oil and MSB medium supplemented with 1% glucose were used for this purpose. The specific activities of the enzymes were determined spectrophotometrically. The growth rate on Sabouraud dextrose agar (SDA), minimal salt agar (MSA) supplemented with starch and MSA supplemented with cellulose were studied. Sensitivity of the isolates to streptomycin and erythromycin was also evaluated. Enzymatic activities were observed in all the isolates, namely, Clitocybe gibba, Gerronema chrysophyllum, Pleurotus porrigens, Clitocybe familia, Auricularia auricular and Lepiota procera. The highest MnP activity was observed in nutrient broth with the best being from Pleurotus porrigens (25.81U/ml) and the least from Lepiota procera (16.55U/ml). While P. porrigens and G. chrysophyllum fully colonized SDA plates, MSA + starch, MSA + cellulose on the third, fourth and fifth day respectively, L. procera grew at a much slower rate. All isolates tested were resistant to the antibiotics. This screening should be extended to more species and enzymes of species presenting best activities characterized for their potential application in various biotechnological fields such as bioremediation. Research towards the development of grain spawns should be encouraged for commercialization purposes.

Keywords

• manganese peroxidase
• mushrooms