Screening of trichoderma strains isolated from rhizosphere samples for laccase production

Abstract

In this study we screened formerly isolated Trichoderma strains for laccase production on solid media
supplemented with two different substrates, ABTS [2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate)] or
guaiacol. We detected outstandingly strong colour changes in the case of three Trichoderma strains in this
experiment. The strains were identified based on internal transcribed spacer (ITS) sequence analysis as T.
asperellum (SZMC 20786 and SZMC 20866) and T. atroviride (SZMC 20780). We also investigated the
production of laccase enzymes in the case of these Trichoderma strains in two types of liquid media. The pH
dependence of the secreted laccases was determined in cell free ferment broths at pH 3.5, 4, 5, 5.5, 6 and 6.5
adjusted with 25 mM succinate buffer. Laccase activities from liquid cultures were measured with ABTS as
substrate. The results showed that the best laccase producer among the investigated Trichoderma strains was
T. atroviride SZMC 20780 under these conditions. This strain shows the highest laccase enzyme activity on
the second day of incubation in a rotary shaker at 25 °C.