Influence of Different Substrates on Lignolytic Enzyme Production in Improved Strains of Wood Ear Mushroom (<em>Auricularia </em>Species)

Abstract

Commercial cultivation of Wood Ear mushrooms (Genus: <em>Auricularia</em>) has not been successful in Nigeria, due to lack of improved strains. Our initial study indicated that this mushroom can be artificially cultivated on different agro-forestry wastes. These waste are utilized through secretion of oxidative and hydrolytic enzyme complexes by the mushrooms. Therefore, strains with increased ability to produce these enzymes and utilize the substrates are desired. Two strains, <em>Auricularia</em> <em>polytricha</em> (strain EW1) and <em>Auricularia subglabra</em> (strain EW2) collected from wilds of Nigeria were mutated by UV- light exposure. Mutant strains were generated from each wild (EW1M1, EW1M2, EW2M1 and EW2M2) types. The ability of these strains to produce hydrolytic enzymes such as xylanases, cellulases and lignin peroxidase was investigated on different carbon sources <em>viz.,</em> maltose, xylose, starch, oat, sawdust, paddy straw, rice grain and wheat bran. Mutant EW2M2 produced the highest amount of cellulases with maltose as substrate (0.444 Uml^-1). The highest xylanase activity was exhibited by mutant (EW2M2) with xylose as the substrate (2.615 Uml^-1). Mutant EW2M2 exhibited the highest lignin peroxidase activity (1.49 Uml^-1) in presence of maltose. Efficient degradation of other agro-industrial wastes also demonstrated that the strains have the ability to utilize complex carbon sources as substrates. This study reports an improved performance of the mutants (EW1M2) and (EW2M2) strains of <em>Auricularia</em> species in oxidative/hydrolytic enzyme production over the wild types.