Production of a Fungistatic Substance by Pseudallescheria boydii Isolated from Soil Amended with Vegetable Tissues and Its Significance
Department of Plant Pathology, National Chung Hsing University, Taichung, Taiwan. Mycopathologia
(Impact Factor: 1.53).
09/2009; 169(2):125-31. DOI: 10.1007/s11046-009-9237-1
Four fungal isolates that were able to use vegetable tissues for multiplication in soil were isolated and identified as Pseudallescheria boydii based on morphological characteristics and ITS sequence similarity. When grown in broth prepared from the same vegetable tissues used in soil amendment, all these isolates of P. boydii produced a substance capable of reducing the disease incidence of black leaf spot of spoon cabbage caused by Alternaria brassicicola and inhibiting the germination of A. brassicicola conidia. The substance, which was fungistatic, was very stable under high temperature and high or low pH value. It was soluble in polar solvents and insoluble in non-polar solvents. Molecular weight estimation and ion exchange ability tests suggest that the fungistatic compound has a molecular weight between 500 and 1,000 and has no charge on its molecule. Results from this study suggest the possession of a strong competitive saprophytic ability by P. boydii, which in turn may explain the widespread occurrence of this human pathogen in soil. Production of a fungistatic substance when P. boydii was grown in broth prepared from vegetable tissues suggests the importance of antibiotic production in its competitive saprophytic colonization of organic matters in soil.
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- "As a matter of fact, both ergosterol and 18:2ω6,9 concentrations in 30-d-old PA microcosms were significantly lower than those found in coeval amended incubation control . This might be concomitantly due to both the limited growth of the inoculant and to the widely known ability of Pseudoallescheria spp. to produce fungistatic substances which also hampered the growth of resident fungi (Ko et al., 2010). On the one hand, and with regard to the impact of Pseudoallescheria sp. on bacterial biota, the absence of significant differences in densities of cultivable heterotrophic and hydrocarbonoclastic bacteria with the non-inoculated and amended incubation control, suggested that the augmented fungus did not negatively affect the bacterial biota. "
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ABSTRACT: The present work was aimed at isolating and identifying the main members of the mycobiota of a clay soil historically contaminated by mid- and long-chain aliphatic hydrocarbons (AH) and to subsequently assess their hydrocarbon-degrading ability. All the isolates were Ascomycetes and, among them, the most interesting was Pseudoallescheria sp. 18A, which displayed both the ability to use AH as the sole carbon source and to profusely colonize a wheat straw:poplar wood chip (70:30, w/w) lignocellulosic mixture (LM) selected as the amendment for subsequent soil remediation microcosms. After a 60 d mycoaugmentation with Pseudoallescheria sp. of the aforementioned soil, mixed with the sterile LM (5:1 mass ratio), a 79.7% AH reduction and a significant detoxification, inferred by a drop in mortality of Folsomia candida from 90 to 24%, were observed. However, similar degradation and detoxification outcomes were found in the non-inoculated incubation control soil that had been amended with the sterile LM. This was due to the biostimulation exerted by the amendment on the resident microbiota, fungi in particular, the activity and density of which were low, instead, in the non-amended incubation control soil.
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- "To study the ability of different adsorptive materials to remove the resistance-activating substances from the mycelium extract, Diaion SK1B cation exchange resins (equivalent to Amberlite 1R-120), Diaion SA 12A anion exchange resins (equivalent to Amberlite 1RA-420) and activated charcoal (Sigma–Aldrich, St. Louis, MO, USA) were washed as previously described to remove possible inhibitory substances (Ko et al., 2010b). An aliquot of 10 ml extract was shaken with 1 g cation exchange resins, anion exchange resins or activated charcoal in a 150-ml flask on a shaker for 24 h and filtered through a Whatman no. 1 filter paper. "
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ABSTRACT: Microorganisms capable of utilizing vegetable tissues for multiplication in soil were isolated, cultivated in liquid medium prepared from the same vegetable tissues, and tested for ability to activate resistance in pepper leaves against Phytophthora blight caused by Phytophthora capsici.
Among the 121 microorganisms isolated, a fungus Humicola phialophoroides showed distinct ability to produce substances capable of activating resistance. The resistance-activating substances produced by H. phialophoroides were mostly retained in the mycelium, and were readily extracted from the mycelium powder with polar solvents. The extract was not inhibitory to zoospore germination or germ tube growth of P. capsici. In pepper leaves, the extract took only about 12 h to activate resistance against P. capsici. After activation, washing treated leaf surface with water did not have much effect on the resistance expression. In addition to being able to move from the upper leaf surface to lower leaf surface, the resistance-activating substances were capable of moving 5 mm acropetally and 10 mm basipetally in pepper leaves, Chromatography of the extract on silica gel column suggests that there are probably more than three components in the extract with resistance-activating ability. The resistance-activating activity of the mycelium extract was not affected by treatment with either cation or anion exchange resins, indicating that none of the active components have positive or negative charges on their molecules.
Results show that H. phialophoroides is capable of producing multiple resistance-activating substances which are mostly retained in the mycelium. The study also indicates that none of the active components have positive or negative charges on their molecules.
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ABSTRACT: Microorganisms capable of utilizing vegetable tissues for growth in soils were isolated and their vegetable broth cultures were individually sprayed directly on leaves to test their ability to control Phytophthora blight of bell pepper caused by Phytophthora capsici. Liquid culture of Streptomyces strain TKA-5, a previously undescribed species obtained in this study, displayed several desirable disease control characteristics in nature, including high potency, long lasting and ability to control also black leaf spot of spoon cabbage caused by Alternaria brassicicolca. The extract was fungicidal to P. capsici but fungistatic to A. brassicicola. It was stable at high temperature and high pH. However, after exposure to pH 2 for 24h, the extract was no longer inhibitory to P. capsici although it was still strongly inhibitory to A. brassicicola. After treatment with cation or anion exchange resins, the extract lost its inhibitory effect against P. capsici but not A. brassicicola. The results suggest that the extract contained two different kinds of inhibitory metabolites, one against P. capsici with both positive and negative charges on its molecule and another against A. brassicicola with no charges on its molecule. The inhibitory metabolites were soluble in ethanol or methanol but not in water, ether or chloroform. They were dialyzable in the membrane tubing with molecular weight cut-off of 10,000, 1000 or 500 but not 100, indicating that the inhibitors have a molecular weight between 500 and 100. Results also showed that both inhibitors are not proteins.
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