Antimicrobial Effect of Ivorian Papaya Seed Extracts (Carica papaya L.) on Pathogenic Bacteria and Mycotoxin-Producing Molds

Abstract

This study evaluated the in vitro antibacterial and antifungal activities of ethanolic seed extracts obtained from two papaya (Carica papaya L.) varieties at different ripening stages. Eight extracts prepared from local and Solo papaya seeds were tested against Escherichia coli, Bacillus cereus, Pseudomonas aeruginosa, and Staphylococcus aureus, and against the moulds Fusarium spp., Aspergillus ochraceus, Aspergillus niger, and Aspergillus flavus. Antibacterial activity was assessed by measuring inhibition zones, whereas antifungal activity was evaluated using surface-application and well-diffusion methods. Antibacterial effects varied according to the extract and bacterial species, with inhibition-zone diameters among active extracts ranging from 8.00 ± 1.00 to 30.33 ± 0.58 mm. Extracts from the local variety were active against E. coli and B. cereus, whereas extracts from the Solo variety showed pronounced activity against P. aeruginosa. None of the extracts inhibited S. aureus. Antifungal activity also differed among extracts and test methods. Surface application resulted in complete inhibition of Fusarium spp. and A. ochraceus by E7. In the well-diffusion assay, E3 reduced A. flavus mycelial growth by 24.56% and showed the greatest inhibition of Fusarium spp., with an inhibition zone of 23.33 ± 5.77 mm and a 44.44% reduction in mycelial growth. Overall, antimicrobial activity varied with papaya variety, ripening stage, extract preparation, microorganism, and assay method.