Lactobacillus casei CRL 431 and Lactobacillus rhamnosus CRL 1224 as biological controls for Aspergillus flavus strains.
ABSTRACT The effect of two species of lactobacilli, Lactobacillus casei CRL 431 and Lactobacillus rhamnosus CRL 1224, on growth of different Aspergillus flavus strains was determined. A. flavus strains (Ap, TR2, or CF80) were grown in LAPTg broth at 37 degrees C for 7 days as a single culture and in association with L. casei CRL 431 or L. rhamnosus CRL 1224 at initial inoculum ratios of 1:1, 1:10, and 1:100. In most cases, the mixed cultures had a lower fungal growth and a lower pH than the control cultures. Mycelial dry weight was reduced to 73 and 85% using L. casei CRL 431 and L. rhamnosus CRL 1224, respectively. The pH decrease in mixed cultures when the fungal mycelial dry weight is reduced may play an important role in inhibition. The number of viable bacteria was variably affected by fungal growth. These results indicate that L. casei CRL 431 and L. rhamnosus CRL 1224 may be useful as potential biocontrol agent against A. flavus.
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ABSTRACT: Mycotoxins such as aflatoxins, fumonisins, trichothecenes, and ochratoxins are contaminants of many agronomic crops worldwide, and cause both economic losses and health effects. The potential of antagonistic microorganisms to be developed into biological control agents has been investigated in several crop systems, as alternatives to chemical fungicides for control of mycotoxigenic fungi. Laboratory and greenhouse studies have identified a number of bacterial, yeast, and filamentous fungal isolates that reduce crop contamination of mycotoxigenic fungi, although investigations of field efficacy have been limited. These studies demonstrate that the diversity of ecological interactions between mycotoxigenic fungi and other resident microorganisms may provide tools for development of biocontrol methods to reduce mycotoxin contamination.01/2008;
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ABSTRACT: The cell-free culture filtrate (CCF) was prepared from a culture of an Aspergillus flavus antagonist, Bacillus subtilis B-FS06. The CCF inhibited the growth and spore germination of A.flavus at a series of concentrations (10, 25, 50%) (v/v). It still retained the activity after treatment at pH values ranging from 2 to 12 for 24h or at 100°C for 30min. The antifungal activity, however, was reduced by 30% after treatment at 121°C for 20min. After purification by anion exchange chromatography, gel filtration chromatography and HPLC, the active compounds revealed six ion peaks: [M–H] m/z=1006.78, 1020.71, 1034.74, 1049.54, 1056.78, and 1071.64 by using electrospray ionization mass spectrometry (ESI-MS) analysis. In the presence of the active compounds at 200μg/g, the growth of A.flavus on peanuts was completely inhibited.World Journal of Microbiology and Biotechnology 01/2008; 24(6):783-788. · 1.35 Impact Factor