Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XIX
Written by Gabriela POPA, Corina BUBUIANU, Georgeta FIDLER, Calina Petruta CORNEA
White rot basidiomycetes are known as producers of several oxidative and hydrolytic enzymes that act together on the degradation of certain components of the plant cell wall. Among these enzymes, laccases represent a family of coppercontaining polyphenol oxidases, and can be involved in various processes such as, morphogenesis, pathogenesis, and lignin degradation. Because of their capability to oxidize a wide range of substrates, fungal laccases are currently studied for their potential agricultural, industrial, and medicinal applications. Hence, the aim of this study was to investigate the efficacy of culture media on laccase production by six white rot fungal species: Ganoderma applanatum, Flammulina velutipes, Hericium coraloides, Laetiporus sulphureus, Pleurotus ostreatus var. Florida, and Trametes versicolor. The white-rot fungi were inoculated in PD broth (potato dextrose) and Hwang et al (2008) medium. Extracellular laccase formation by these fungi was recorded by spectrophotometry using guaiacol as substrate. During 30 days of incubation was found that laccase production reached maximum values in the filtrates of both culture media and declined along incubation period. PD medium was optimum for laccase producing white-rot fungi. The maximum laccase activity was obtained from the culture filtrates of Trametes versicolor and Hericium coraloides. The optimal culture medium for laccase producing fungi was PD broth. Also, pH values of the fungal culture media were changed during incubation period. The minimal pH values were recorded in culture filtrates of Laetiporus sulphureus (2.8 and 2.4). The highest laccase activity was detected at pH values between 5.0 and 6.0 in PD medium. A good biomass yield was recorded by Pleurotus ostreatus var. Florida grown on both media tested. It was found that a high production of laccase did not dependent on high biomass yields.
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