Activity of a novel compound produced by Aspergillus parasiticus in the presence of red flour beetle Tribolium castaneum against Pseudomonas aeruginosa and coleopteran insects

Abstract

Aspergillus is a promising source of bioactive secondary metabolites. The addition of insect-derived material in the broth culture could trigger the biosynthesis of insecticidal and antimicrobial compounds by entomopathogenic fungus (EF). Insects inhabit diverse niches and interact with various bacteria, for this reason, when a fungus kills an insect should inhibit the insect?s gut bacteria to prevent the insect consumption by bacteria. According with this hypothesis, the EF is able to produce substances that inhibit bacteria growth or bacteria virulence strategies. In the present, investigation is demonstrated that the addition of Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) components (2 % w/v) in a culture of saprophytic fungus Aspergillus parasiticus MOR 3 induces the production of a novel compound present inside mycelium 2-(4-bromophenyl)-2-oxoethyl benzoate, that is reported here for the first time as a natural product of A. parasiticus. In addition, increased significantly the fungal extracellular production of undecyl 4-fluorobenzoate. The mycelium extract (ME) at 250 μg per g of diet on adult population of T. castaneum produced an alteration of the feeding behavior of coleopteran insects (Repellency index = +30). The fraction derived from ME (Fr2) that contained the organobromine compound, 2-(4-bromophenyl)-2-oxoethyl benzoate had the highest inhibition of the Pseudomonas aeruginosa virulence factors like elastase enzyme (49 %) at 5 μg/ml and biofilm formation (43 %) at 100 μg/ml. The results suggest that the extract from mycelium of a non-aflatoxigenic A. parasiticus MOR 3 strain is a potential candidate as food coleopteran repellent as well as an anti-virulence strategy of P. aeruginosa.