Degradation of linuron in soil by two fungi

Two fungal strains were applied to soil polluted with herbicide in order to determine their degradation potential. Three experimental setups were used. In the first setup, the soil in pots was contaminated by linuron in final concentration of 1 ppm. Suspensions of Phanerocheate chrysosporium and Trichoderma asperellum were applied sepa­rately or in combination. Tomato plantlets were transplanted and chlorophyll content in their leaves was determined at two time points during plant growth. In the second setup in pots, the final concentration of linuron was lower, 0.45 ppm. In the third setup 0.1 ppm of linuron was applied in the field plot. Plantlets of lettuce were transplanted and chlorophyll content was measured as indicator of plant stress. The content of linuron in soil was determined by HPLC. The applied fungal strains significantly reduced toxic effect of 0.45 ppm linuron on plants, which was not the case for 1 ppm linuron. Both fungi, applied separately or in combination, were effective in decreasing the linuron content in the soil. However, in field conditions the combination of both fungi was the most effective. [Projekat Ministarstva nauke Republike Srbije, br. III43010

Effect of the edaphic factors and metal content in soil on the diversity of Trichoderma spp.

Influence of edaphic factors and metal content on diversity of Trichoderma species at 14 different soil sampling locations, on two depths, was examined. Forty-one Trichoderma isolates from 14 sampling sites were determined as nine species based on their internal transcribed spacer (ITS) sequences. Our results indicate that weakly alkaline soils are rich sources of Trichoderma strains. Also, higher contents of available K and P are connected with higher Trichoderma diversity. Increased metal content in soil was not inhibiting factor for Trichoderma species occurrence. Relationship between these factors was confirmed by locally weighted sequential smoothing (LOESS) nonparametric smoothing analysis. Trichoderma strain (Szeged Microbiology Collection (SZMC) 22669) from soil with concentrations of Cr and Ni above remediation values should be tested for its potential for bioremediation of these metals in polluted soils

Screening of Trichoderma strains isolated from rhizosphere samples for laccase production

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