Biodiversity of laccase producing fungi in Egypt

Laccase enzyme (EC 1.10.3.2) is a benzenediol, a multi-copper enzyme, and one of the three main ligninases that differs from the others in its ability to catalyze the oxidation of lignin components. It is widely distributed in fungi and because of its importance in bioremediation; the search for fungal laccases with different properties and potential applications is still on-going. In view of its importance in large scale application, the present endeavor is to search for highly efficient laccase producing fungi from different environmental habitats in Egypt. Cultural conditions such as temperatures, pH, carbon sources and nitrogen sources were optimized for the production of high extracellular laccase activity. By screening sources under investigation namely: soil, wood, seaweeds, sponge, ascidia, drifted decaying wood, plants and miscellaneous materials it vas possible to encounter as many as 60 species belonging to 33 genera. Zygomycota repreented by six species (10.16% of the total species number), teleomorphic Ascomycot:t (9 species, anamorphic Ascomycota (44 species, 74.57%) and Basidiomycota (1 species, 1.69%). Soil showed the highest Simpson's species diversity index of 0.83 while contaminated wax samples and Adiantum capillus-veneris showed the lowest value (0). All iolated taxa were tested for laccase production using a qualitative plate assay method by using guaiacol as color indicator. Sixteen isolates showed positive reaction indicating alignin-degrading potentiality and out of them eight measured the highest zone diameter with high oxidation scale. The most promising taxa were endophytic namely: Chaetomium globosum, Phoma exigua, Thanatephoru. cucumeris and Sordaria fimicola. PH 7, incubation temperature 30°C, 1 % maltose and 0.3o peptone supported the highest biomass and laccase production for Chaetomium globsum.