Antifungal Effect of Streptomyces 702 Antifungal Monomer Component DZP8 on Rhizoctonia solani and Magnaporthe grisea

The aim of this study was to investigate the in vitro antifungal effects of antifungal monomer component DZP8 isolated from Streptomyces 702 on the mycelium growth, sclerotium formation and germination of Rhizoctonia solani and on the mycelium growth, conidial formation, germination, appressorium formation of Magnaporthe grisea. The results showed that the antifungal monomer component DZP8 has strong antifungal effect on both the R. solani and M. grisea. The EC50 and EC90 of DZP8 were 1.81 and 3.35 μg/ml on Ft. solani respectively, and 37.01 and 136.21 μg/ml on M. grisea respectively. Under the treatment of 48.01 μg/ml DZP8, the sclerotium formation rate of R. solani was just 39.21%, the formation time delayed by 216 h and the dry weight decreased by 81.37% in comparison the con- trol; and 33.51 μg/ml DZP8 significantly inhibited the sclerotium germination. In the presence of 160.08 μg/ml DZP8, the sporulation of M. grisea was just 9.29% of control sample; 20.14 μg/ml DZP8 inhibited the conidial germination suppression rate by 95.16%, and the appressorium formation by 100%.

High Thermoelectric Figure of Merit of Ag8SnS6 Component Prepared by Electrodeposition Technique

A new thermoelectric material Ag8SnS6, with ultra-low thermal conductivity in thin film shape, is prepared on indium tin oxide coated g/ass （ITO） substrates using a chemical process via the electrodeposition technique. The structural, thermal and electrical properties are studied and presented in detail, which demonstrate that the material is of semiconductor type, orthorhombic structure, with a band gap in the order of 1.56eV and a free carrier concentration of 1.46 × 10^17 cm-3. The thermal conductivity, thermal diffusivity, thermal conduction mode, Seebeck coefficient and electrical conductivity are determined using the photo-thermal deflection technique combined with the Boltzmann transport theory and Cahill＇s model, showing that the AgsSnS6 material has a low thermal conductivity of 3.8 Wm - 1K- 1, high electrical conductivity of 2.4 × 10^5 Sm- 1, Seebeck coefficient of -180μVK-1 and a power factor of 6.9mWK-2m-1, implying that it is more efficient than those obtained in recently experimental investigations for thermoelectric devices.

Inhibition Mechanism of Antifungal Monomer DZP8 against Rhizoctonia solani

In order to study the inhibition mechanism of antifungal monomers DZP8 produced by streptomyces 702 strain against Rhizoctonia solani, the effects of DZP8 on mycelial morphology were investigated under light microscope, and the effects of DZP8 on mycelial inclusion leakage and cell membrane damage of myceli-um were determined. The results showed that DZP8 caused a series of changes in mycelial morphology of R. solani in liquid culture condition. DZP8 treatments with concentrations of 1.81 and 3.35 μg/mL for 24 h caused big vacuole, rough surface and more inclusions of mycelium. With the treatment time prolonging, the mycelium distorted and appeared irregular constriction. DZP8 treatment with concentration of 20.10 μg/mL led to the increase of conductivity of mycelium culture liquid, leakage of soluble sugar and protein, and the lipid peroxidation of mycelium membrane. It was found that DZP8 at a very low concentration could cause changes of mycelial morphology of R. solani, while only a certain concentration could cause significant damage to cell membrane. This indicated that cell membrane might be one of the action sites of DZP8, and it might have other action sites or mechanism.