Biocontrol of toxinogenic and f. sp. by two rare Saharan actinomycetes strains and LC-ESI/MS-MS profiling of their antimicrobial products.

Fungi colonizing fruits in the field and post-harvest constitute a major threat to the global food sector. This study focuses on the biocontrol of (aflatoxin-producing mold considered carcinogenic by IARC) and f. sp. albedinis (FOA) (phytopathogenic agent, causal of El Bayoud in the Algerian and Moroccan Sahara). These molds have a significant economic impact and pose a serious human health problem. The aim of this work is to study the antifungal activity of two rare actinomycetes strains; sp. COL22 and sp. COL08 strains against toxinogenic and . f. sp. albedinis. The strains are isolated from rhizosphere on different media: ISP2, GLM, TSA, Starch-casein-agar and WYE and with different treatments of the samples (physical, chemical treatment and enrichment). The antifungal tests against the pathogenic microorganisms were performed on ISP2, GLM and TSA medium by means of the agar cylinders method. The kinetics of antibiotic production were performed on ISP medium over 16 days. The characterization of the antimicrobial compounds by LC-ESI/MS-MS showed that the bacterial extracts contain Antibiotic SF 2738C, Tetrodecamycin and Aplysillamide B. The phenotypic and molecular studies showed that sp. COL22 is closely related to the strain type and that sp. COL08 is closely related to the strain type. The two strains are rare and showed an interesting activity against toxinogenic and f. sp. albedinis.