Résumé:
The exploration of apples and apricots fruit samples from the Wilaya of Batna located in eastern Algeria (Aris and N'gaous) yielded 23 fungal isolates; three of them were selected as potential producers of mycotoxins by the antagonism test against sensitive bacteria. Morphological and molecular identification (DNA-ITS / β-tubulin analysis) of the isolates showed that they were 3 strains of Penicillium expansum, registered at GenBank under accession numbers MT023795, MN904449 and MN904448. The ability of these three strains to produce mycotoxins in vitro on YES liquid fermentation medium has made it possible to demonstrate the secretion of several secondary metabolites, including patulin. The use of the GC-MS technique for the identification of the various metabolites contained in the liquid cultures of the three strains revealed the presence of patulin in the three extracts, and those three isolates are known to be patulin-producing. The in vivo pathogenicity test by inoculation of spore suspensions of the three strains of Penicillium expansum in healthy apples belonging to the varieties Golden delicious and Fuji, revealed the appearance of typical symptoms of blue rot in apples in post-harvest. The ability to produce patulin in vivo by the three pathogens was performed by the same previous test, using the Golden delicious variety only. This test revealed that Penicillium expansum (MN904448) is the most virulent strain, inducing large diameter lesions and a remarkable rate of disease development compared to the other two strains. Furthermore, this strain is capable of producing a large quantity of patulin at 25 °C in 9 days reaching 469.4 µg / mL, the strain Penicillium expansum (MT023795) produces 360 µg / mL, while Penicillium expansum (MN04449) seems to produce the least important quantity estimated at 3 µg / mL. Research for patulin in the tissues of apples naturally infected with blue rot, intended for direct consumption, has shown the contamination of locally produced apples by patulin and its role as a biomarker of effect has been developed and deemed reliable. . Indeed, evaluation of the ability of patulin to diffuse into healthy apple tissue from the rotten area revealed the presence of patulin in visually healthy areas even after removing the entire infected area. This test is, moreover, supposed to be reliable as a biomarker of effect in the field of the diffusion of mycotoxins in fruits intended for consumption.
