Compost Seed of Trichoderma harzianum UD12-102 in Controlling Collar and Stem Rot of Tomato Caused by Sclerotium rolfsii

Antagonistic fungus, Trichoderma harzianum UD12-102, exhibited 90% inhibition against Sclerotium rolfsii in vitro and 80% survival of tomatoes infected by S. rolfsii in vivo. Moreover, the antagonistic fungi increased the effectiveness of a commercial fungicide (vitavax) in controlling S. rolfsii in tomatoes. In field experiments, composts were used as carriers for T. harzianum UD12-102 inoculum preparation. Following S. rolfsii inoculation, the survival percentages of tomato plants were not significantly different with all treatments receiving T. harzianum UD12-102 antagonist. However, the inoculum prepared with compost B (inoculated the antagonist at beginning of composting) resulted in a high survival percentage (more than 60%) with 4 weeks of infection, while the survival percentage of control plants dramatically decreased on week 2 (8.35%), and the plants died after 3 weeks due to S. rolfsii. The compost was a good alternative carrier for antagonistic fungi inoculation and was friendly with soil environments

A halotolerant laccase from Chaetomium strain isolated from desert soil and its ability for dye decolourization

13 p.-6 fig.-3 tab.A novel fungal laccase produced by the ascomycete Chaetomium sp. isolated from arid soil was purified and characterized and its ability to remove dyes was determined. Extracellular laccase was purified 15-fold from the crude culture to homogeneity with an overall yield of 50% using ultrafiltration and anion-exchange chromatography. The purified enzyme was found to be a monomeric protein with a molecular mass of 68 kDa, estimated by SDS-PAGE, and with an isoelectric point of 5.5. The optimal temperature and pH value for laccase activity toward 2,6-DMP were 60 °C and 3.0, respectively. It was stable at temperatures below 50 °C and at alkaline conditions. Kinetic study showed that this laccase showed higher affinity on ABTS than on 2,6-DMP. Its activity was enhanced by the presence of several metal ions such as Mg2+, Ca2+ and Zn2+, while it was strongly inhibited by Fe2+, Ag+ and Hg2+. The novel laccase also showed high, remarkable sodium chloride tolerance. Its ability to decolorize different dyes, with or without HBT (1-hydroxy-benzotriazole), as redox mediator, suggests that this protein may be useful for different industrial applications and/or bioremediation processes.Peer reviewe