Studies on the inhibitory properties of leaf ethanolic extracts obtained from Ficus (Moraceae) species against Aeromonas spp. strains

Introduction The most frequently isolated bacteria in Polish aquaculture are of the Aeromonas genus; also pathogenic to human fish consumers, they cause substantial economic losses, and require antibiotic therapy to treat. Antibiotic residues in animal-derived food provoke concern. The aim of the study was to appraise the antimicrobial activity of ethanolic extracts of Ficus plant species against Aeromonas strains. Material and Methods Leaves of 41 Ficus species were collected from two Ukrainian botanic gardens. They were crushed, washed, homogenized in ethanol and centrifuged, and the supernatants were applied in the Kirby-Bauer disc-diffusion method to assess the susceptibility to them of Aeromonas hydrophila, A. sobria, and A. salmonicia subsp. salmonicida isolates confirmed as K886, K825, and St30 strains. Analogous assessment was also made of these bacteria's susceptibility to sulfonamides, quinolones, tetracyclines, and one amphenicol. Data were analysed statistically. Results The majority of the extracts considerably inhibited bacterial growth, A. sobria being susceptible to 14 Ficus species, A. salmonicida subsp. salmonicida to 13, and A. hydrophila to 10. Conclusion Treatment with plant extracts has promise as an alternative to antibiotic therapy. Botanic gardens may offer new sources of plant-derived agents with a broad spectrum of biological and antimicrobial action. Further research will be useful to broaden knowledge of Ficus' therapeutic potential.