Résumé :
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Metal trace elements (MTE) contamination is an increasingly major concern for public health, causing complications associated with cancers and foetal malformities. Fusarium crown rot and Fusarium head blight are two diseases caused by the phytopathogen Fusarium culmorum, leading to economic losses, and reduction in crop quality by mycotoxin contamination. To counter these issues, bacterial agents with diverse metabolic capacities, antifungal weaponry, and adaptability to various environments were looked for, where in this study, the strains Pseudomonas laurentiana M11 and Bacillus atrophaeus B16 were brought to light. The M11 and B16 strains were evaluated for their capability to chelate and tolerate MTEs in vitro as well as their antifungal competence. MTE’s chelation efficiency was determined using the murexide-Zn/Cu reduction assay in which the colour density of the murexide-ions complex was measured spectrophotometrically. Both strains exhibited an exceptional chelation potential with a maximum of 93% in the presence of 25μg/l for ZnCl2 and 91% at 100μg/l for CuSO4, outperforming even the EDTA standard. Both strains proved to be very resistant to copper and zinc considering that the studied concentrations did not result in a complete elimination of bacteria; however, inhibition was recorded at a minimum concentration of 1000μg/l for both ZnCl2 and CuSO4. Even though F. culmorum was dominant at higher concentrations when incubated with bacteria, the M11 strain was able to cause an important growth delay of 8 days at 500μg/l. On the other hand, the B16 strain completely prevented the fungal growth at 250μg/l and caused an inhibition zone at 500μg/l of copper and zinc.
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