Efficacy of metabolites of a Streptomyces strain (AS1) to control growth and mycotoxin production by Penicillium verrucosum , Fusarium verticillioides and Aspergillus fumigatus in culture

The objectives of this study were to determine the efficacy of metabolites of aStreptomyces strain AS1 on (a) spore germination, (b) mycelial growth, (c) control of mycotoxins produced byPenicillium verrucosum (ochratoxin A, OTA),Fusarium verticillioides (fumonisins, FUMs) andAspergillus fumigatus (gliotoxin) and (d) identify the predominant metabolites involved in control. Initial screening showed that theStreptomyces AS1 strain was able to inhibit the mycelial growth of the three species at a distance, due to the release of secondary metabolites. A macroscopic screening system showed that the overall Index of Dominance against all three toxigenic fungi was inhibition at a distance. Subsequent studies showed that the metabolite mixture from theStreptomyces AS1 strain was very effective at inhibiting conidial germination ofP. verrucosum, but less so against conidia ofA. fumigatus andF. verticillioides. The efficacy was confirmed in studies on a conducive semi-solid YES medium in BioScreen C assays. Using the BioScreen C and the criteria of Time to Detection (TTD) at an OD  = 0.1 showed good efficacy againstP. verrucosum when treated with theStreptomyces AS1 extract at 0.95 and 0.99 water activity (aw) when compared to the other two species tested, indicating good efficacy. The effective dose for 50% control of growth (ED50) at 0.95 and 0.99aw were approx. 0.005  ng/ml and 0.15 μg/ml, respectively, with the minimum inhibitory concentration (MIC) at bothaw levels requiri...
Source: Mycotoxin Research - Category: Toxicology Source Type: research