In-vitro Application of a Qatari Burkholderia cepacia strain (QBC03) in the Biocontrol of Mycotoxigenic Fungi and in the Reduction of Ochratoxin A biosynthesis by Aspergillus carbonarius.

Randa Zeidan,Zahoor Ul-Hassan,Roda Al-Thani,Quirico Migheli,Samir Jaoua

doi:10.3390/toxins11120700

Abstract

Mycotoxins are secondary metabolites produced by certain filamentous fungi, causing human and animal health issues upon the ingestion of contaminated food and feed. Among the safest approaches to the control of mycotoxigenic fungi and mycotoxin detoxification is the application of microbial biocontrol agents. Burkholderia cepacia is known for producing metabolites active against a broad number of pathogenic fungi. In this study, the antifungal potential of a Qatari strain of Burkholderia cepacia (QBC03) was explored. QBC03 exhibited antifungal activity against a wide range of mycotoxigenic, as well as phytopathogenic, fungal genera and species. The QBC03 culture supernatant significantly inhibited the growth of Aspergillus carbonarius, Fusarium culmorum and Penicillium verrucosum in PDA medium, as well as A. carbonarius and P. verrucosum biomass in PDB medium. The QBC03 culture supernatant was found to dramatically reduce the synthesis of ochratoxin A (OTA) by A. carbonarius, in addition to inducing mycelia malformation. The antifungal activity of QBC03’s culture extract was retained following thermal treatment at 100 °C for 30 min. The findings of the present study advocate that QBC03 is a suitable biocontrol agent against toxigenic fungi, due to the inhibitory activity of its thermostable metabolites.

Highlights

Mycotoxins are natural contaminants produced by certain filamentous fungi, mainly belonging to the genera Aspergillus, Penicillium, and Fusarium
The antagonistic spectrum of QBC03 was explored against 21 fungal species belonging to the Aspergillus, Fusarium and Penicillium genera, using a spore overlay method
Among the tested fungal genera, Aspergillus and Penicillium showed higher sensitivity compared to Fusarium

Summary

Introduction

Mycotoxins are natural contaminants produced by certain filamentous fungi, mainly belonging to the genera Aspergillus, Penicillium, and Fusarium. The contamination of food commodities with toxigenic fungal species, either at pre- or post-harvest (transportation, storage) phases, leads to the accumulation of their toxic secondary metabolites [1,2]. OTA, the most toxic among the ochratoxins, is a secondary metabolite of some Aspergillus (A. carbonarius, A. ochraceus, A. westerdijkiae and A. niger) and Penicillium (P. verrucosum, P. nordicum) species [7]. The contamination of these fungi leads to the accumulation of mycotoxin in a variety of food and feed products including cereals, fruits juices, animal feed, wine, and baby food [8,9,10].

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