Production of a Fungistatic Substance by Pseudallescheria boydii Isolated from Soil Amended with Vegetable Tissues and Its Significance

Abstract

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.

Pseudaboydins A and B: Novel Isobenzofuranone Derivatives from Marine Fungus Pseudallescheria boydii Associated with Starfish Acanthaster planci

“…Pseudallescheria boydii is deemed to be a human pathogenic fungus and can cause a variety of infections, especially in the immunocompromised and immunocompetent patients. However, up to now, the literature reports on the secondary metabolites of this fungus are still limited [8,9,10,11,12,13]. The literature survey prompted us to investigate the metabolites of the fungus, Pseudallescheria boydii .…”

Multiple resistance-activating substances produced by Humicola phialophoroides isolated from soil for control of Phytophthora blight of pepper

“…), and tubers of sweet potato [ Ipomoea batatas (L.) Lam. ], for multiplication in soil were isolated as previously described (Ko et al,2010b). …”

“…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.…”

Activity and characterization of secondary metabolites produced by a new microorganism for control of plant diseases

“…The inoculation method described by Ko et al [16] was used in this study. Each bell pepper leaf was inoculated with five 2-ml drops of zoospore suspension of P. capsici along the edge of the leaf, and a 10-ml drop of molten agar consisting of 1% agar and 1% V-8 juice at 60 8C was added to each inoculum drop to fix the inoculum on the target site.…”