Biogenic synthesis of silver nanoparticles using Gliocladium deliquescens and their application as household sponge disinfectant.

The topic of this investigation was to evaluate the microbial contamination of household sponges, biosynthesize of silver nanoparticles (Ag NPs) by Gliocladium deliquescens cell-free supernatant, and estimate the efficiency of Ag NPs as an acceptable disinfectant. The 23 factorial design was applied for the optimization of Ag NPs synthesis. Silver nitrate (AgNO3) concentration was the main positive impact on Ag NP biosynthesis. Various gamma irradiation doses were used in Ag NP production where the highest yield production was at 25.0 kGy. Ag NPs were characterized by UV-Vis. spectroscopy, The Fourier-transform infrared spectroscopy analysis (FTIR), dynamic light scattering (DLS), X-ray diffraction (XRD), and transmission electron microscope (TEM). Ag NPs were monodispersed spherical-shaped with 9.68 nm mean size. Two hundred sponge samples that were collected from different Egyptian household furniture and kitchens were highly contaminated by various contaminants including Salmonella spp., Staphylococcus spp., coliform bacteria, Gram-negative bacteria, yeasts, and molds. Ag NPs showed functional antimicrobial activity against all the microbial contaminants; Salmonella spp. was completely inhibited by Ag NP (50.0 µg/mL) treatment. The Ag NPs have the maximum inhibition zone against Salmonella spp. (14 mm) compared with the Staphylococcus spp. (12.3 mm). The minimum inhibitory concentration (MIC) of Ag NPs against Salmonella spp. and Staphylococcus spp. were 6.25 µg/ mL and 12.5 µg/ mL, respectively. The antibiofilm activity of Ag NPs was the highest at the concentration of 50.0 µg/mL recording 63.3 % for Salmonella spp. and 54.5 % for Staphylococcus spp. Ag NPs may find potent disinfectant applications for household purposes.

[Genetic transformation of the fungus Gliocladium sp. mediated by Agrobacterium tumefaciens].

OBJECTIVE: To construct a transformation system in Gliocladium sp. 6.102, a Cordyceps-colonizing fungus producing a variety of epipolythiodioxopiperazine (ETP) compounds with drug potentials. METHODS: Agrobacterium tumefaciens-mediated transformation (ATMT) was used to transform Gliocladium sp. 6.102. The factors of bacterial cell concentration, co-cultivation time, pH and acetosyringone concentration were optimized. RESULTS; A total of 50 -100 transformants per 10(6) fungal conidia was obtained via the optimal ATMT method. The genes encoding hygromycin B phosphotase and enhanced green fluorescent protein (EGFP) were transferred into Gliocladium sp. by the optimal ATMT method. The marker genes were successfully expressed and stably maintained in the transgenic fungus. CONCLUSION: A transformation system was established for Gliocladium sp. 6.102 and this system may be useful to identify ETP biosynthetic genes in Gliocladium.

Quantitative isolation of biocontrol agents Trichoderma spp., Gliocladium spp. and actinomycetes from soil with culture media.

Soil biodiversity plays a key role in the sustainability of agriculture systems and indicates the level of health of soil, especially when considering the richness of microorganisms that are involved in biological control of soilborne diseases. Cultural practices may produce changes in soil microflora, which can be quantified through the isolation of target microorganisms. Rhizosphere soil samples were taken from an assay with different crop rotations and tillage systems, and populations of Trichoderma spp., Gliocladium spp. and actinomycetes were quantified in order to select the general and selective culture media that better reflect the changes of these microbial populations in soil. The most efficient medium for the isolation of Trichoderma spp. and Gliocladium spp. was potato dextrose agar modified by the addition of chloramphenicol, streptomycin and rose bengal, and for actinomycetes was Küster medium, with cycloheximide and sodium propionate.

Fungistatic activity of iron-free bovin lactoferrin against several fungal plant pathogens and antagonists.

Lactoferrin (LF) is a member of the transferrin family of iron-binding glycoproteins. It is also a multifunctional protein of 80 kDa that is synthesized by glandular epithelial cells and secreted into mucosal fluid. High levels of LF are present in colostrom and milk and low levels in tears, saliva, and gastrointestinal and reproductive secretions. Data regarding the antifungal effects of LF are limited. Studies have been performed on Candida albicans, which demonstrated that LF inhibits the growth of this fungus. This study reports the results of experiments carried out in order to evaluate the effects of LF on the growth of 11 fungi, which were isolated from plants and soils. These experiments employed the methods of amended agar utilizing nine different concentration levels of LF (0, 0.001, 0.01, 0.1, 1, 10, 100, 1000, 5000 mg L(-1)). The effects of LF on the growth of these fungi were based on measures of the radial growth of the fungal colonies expressed both as percentage of inhibition and as IC(50) values (the concentration at which the fungal growth was inhibited by 50% relative to controls). LF had no effects on Alternaria alternata, Gliocladium roseum, Fusarium solani and Colletotrichum lindemuthianum. It did, however, inhibit the growth of Aspergillus niger, Trichoderma viride, Sclerotinia sclerotiorum, Sclerotium rolfsii, Rhizoctonia solani and Phoma exigua to the point that their IC(50) values ranged from 31.1 mg L(-1) for S. sclerotiorum to 952 mg L(-1) for T. viride.

[Studies on purification and properties of antagonistic protein from bacteria SS02 of Paenibacillus daejeonensis].

The antifungal, anti-bacterical, anti-brine shrimp activities of SD22 isolated from Paenibacillus daejeonensis Bacteria SS02 were studied. The separation steps included ultracentrifugation, ultrafiltration and (NH4)2SO4 fractional precipitation, further purification was performed by SephadexG-75 and DEAE-32 chromatography. Its molecular weight determined by SDS-PAGE was 56.0 kD and its isoelectfic point was 6.4. SD22 was thermostable to some extent and stable to ultraviolet, but sensitive to some of the enzyme. SD22 could kill most pathogens from propagation, such as Rhizoctonia cerealis, Sclerotinia sclerotiorum Physalospora piricala, Trichodema viride, Gliocladium viride, Curvularia leaf spot, Fusarium sp, Fusarium head blight, Beauveria Bassiana, Escherichia coli, Staphylococcus aureus, Bacillus subtilis , Candidal vaginitis, Fusarium oxysporum Schl. emend. Sayder & Hansem et al. The results will be helpful to find out a novel antifungal protein.

Role of zearalenone lactonase in protection of Gliocladium roseum from fungitoxic effects of the mycotoxin zearalenone.

Zearalenone is a mycotoxin with estrogenic effects on mammals that is produced by several species of Fusarium. We found that zearalenone and its derivatives inhibit the growth of filamentous fungi on solid media at concentrations of < or =10 microg/ml. The fungitoxic effect declined in the order zearalenone > alpha-zearalenol > beta-zearalenol. The mycoparasitic fungus Gliocladium roseum produces a zearalenone-specific lactonase which catalyzes the hydrolysis of zearalenone, followed by a spontaneous decarboxylation. The growth of G. roseum was not inhibited by zearalenone, and the lactonase may protect G. roseum from the toxic effects of this mycotoxin. We inactivated zes2, the gene encoding zearalenone lactonase in G. roseum, by inserting a hygromycin resistance cassette into the coding sequence of the gene by means of Agrobacterium tumefaciens-mediated genetic transformation. The zes2 disruption mutants could not hydrolyze the lactone bond of zearalenone and were more sensitive to zearalenone. These data are consistent with a hypothesis that resorcylic acid lactones exemplified by zearalenone act to reduce growth competition by preventing competing fungi from colonizing substrates occupied by zearalenone producers and suggest that they may play a role in fungal defense against mycoparasites.

[Allelopathic effect of root exudates on pathogenic fungi of root rot in continuous cropping soybean].

Allelopathic effect of root exudates on pathogenic fungi of root rot in continuous cropping soybean was studied by sand culture, water culture, and indoor culture experiments. The results showed that allelopathic promotion of root exudates on the growth of Fusarium semitectum, Gliocladium roseum and Fusarium oxysporum, especially Fusarium semitectum reached significant level or especially significant level in continuous cropping soybean compared with the control. Allelopathic promotion of root exudates on the growth of Fusarium semitectum and Gliocladium roseum in continuous cropping soybean was distinctly larger than that in rotation soybean, and the difference reached significant level under their low concentration. Allelopathic promotion of high concentration of root exudates on the growth of Fusarium semitectum was smaller than that of low concentration of root exudates, and the difference reached significant level in continuous cropping soybean. Allelopathic inhibition of high concentration of phthalic acid and propanedioic acid (L5 and B5) on the growth of Fusarium semitectum. Gliocladium roseum and Fusarium oxysporum, especially Fusarium semitectum reached significant level or especially significant level compared with the control. However, allelopathic promotion of low concentration of phthalic acid and propanedioic acid on the growth of Fusarium semitectum, Gliocladium roseum and Fusarium oxysporum partly reached significant level.