Abstract
Crop contamination by aflatoxin B1 is a current problem in tropical and subtropical regions. In the future, this contamination risk may be expanded to European countries due to climate change. The development of alternative strategies to prevent mycotoxin contamination that further contribute to the substitution of phytopharmaceutical products are thus needed. For this, a promising method resides in the use of biocontrol agents. Several actinobacteria strains have demonstrated to effectively reduce the aflatoxin B1 concentration. Nevertheless, the molecular mechanism of action by which these biological agents reduce the mycotoxin concentration has not been determined. The aim of the present study was to test the potential use of Streptomyces roseolus as a biocontrol agent against aflatoxin B1 contamination. Co-cultures with Aspergillus flavus were conducted, and the molecular fungal response was investigated through analyzing the q-PCR expression of 65 genes encoding relevant fungal functions. Moreover, kojic and cyclopiazonic acid concentrations, as well as morphological fungal changes were also analyzed. The results demonstrated that reduced concentrations of aflatoxin B1 and kojic acid were respectively correlated with the down-regulation of the aflatoxin B1 gene cluster and kojR gene expression. Moreover, a fungal hypersporulated phenotype and a general over-expression of genes involved in fungal development were observed in the co-culture condition.
Highlights
Aspergillus flavus is an opportunist soil pathogen fungus that is implicated in contamination issues in the agriculture field and causes important economic losses [1]
Contamination by aflatoxins frequently occurs with cyclopiazonic acid (CPA), another mycotoxin commonly produced by A. flavus strains that was demonstrated to be a cytotoxic agent in humans [7,8]
In the co-culture condition, the High-Performance Liquid Chromatography (HPLC) analysis demonstrated a reduction in the kojic acid (KA) concentration of 37%
Summary
Aspergillus flavus is an opportunist soil pathogen fungus that is implicated in contamination issues in the agriculture field and causes important economic losses [1]. This species is commonly found in crops such as maize, soybean, as well as oilseed, peanuts, dried fruits, and spices. A. flavus produces a large number of secondary metabolites including several mycotoxins which impact the food sanitary quality. In this context, aflatoxin B1 (AFB1 ) is recognized as the most potent naturally occurring carcinogenic agent [2]. The massive use of such products has led to the accumulation of toxic chemical residues in agricultural products as well as in water and soil [10]
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