A comparative assessment of the antibacterial activity of extracts derived from leaves of various Ficus species (Moraceae) against fish pathogens

The aim of the study was to compare the in vitro antibacterial activity of leaf extracts obtained from various Ficus species against four bacterial strains of fish pathogens (Serratia liquefaciens, Yersinia ruckeri, Pseudomonas fluorescens, Shewanella putrefaciens). In vitro tests for antibacterial activity assessment revealed that various Ficus species have notable antibacterial efficacy. The six most effective Ficus plants against S. liquefaciens that caused a zone of inhibition of at least 15 mm were F. lingua, F. erecta, F. rubiginosa, F. tinctoria, F. sur, and F. aspera. The maximum antimicrobial activity against the Y. ruckeri strain was observed for ethanolic extracts of F. hederacea, F. formosana, and F. hispida. Our results also demonstrated that the Pseudomonas fluorescens strain exhibited high susceptibility to ethanolic extracts derived from 20 plants (the mean value of inhibition zone diameters (IZD) was more than 15 mm). F. erecta, F. sur, and F. virens extracts were more effective against P. fluorescens. The Shewanella putrefaciens strain revealed a high level of susceptibility to ethanolic extracts derived from the leaves of 32 species (the highest value of the IZDs was observed for F. erecta). The data presented in the current study indicated that ethanolic extracts derived from leaves of various Ficus species are a promising alternative to the use of antibiotics and chemotherapeutics in controlling infections caused by the Serratia liquefaciens, Yersinia ruckeri, Pseudomonas fluorescens, and Shewanella putrefaciens strains.