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ABSTRACTThe aim of this study was to evaluate the antimicrobial activity of Lippia sidoides, Ocimum gratissimum and Zingiber officinale‘sessential oils against Aeromonas spp. isolates from Colossoma macropomum,and to determine their chemical composition. Essential oils were obtained through hydrodistillation and their chemical composition analyzed using gas chromatography coupled to mass spectrometry. The antimicrobial activity of the oils was evaluated by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The major compounds were thymol (76.6%), p-cymene (6.3%) and (E)- β-caryophyllene (5.0%) in L. sidoides;eugenol (43.3%), 1,8-cineole (28.2%) and β-selinene (5.5%) in O. gratissimum;and geranial (23.2%), neral (16.7%) and 1,8-cineole (15.8%) in Z. officinale.All the essential oils evaluated showed bactericidal action against isolates of Aeromonasspp., with MIC and MBC ranging from 625 to 5,000 μg mL−1. We highlight the L. sidoides oil with the best antimicrobial activity (MIC and MBC ranging from 625 to 1,250 μg mL−1).

ABSTRACTThe chemical composition of the essential oils of Mentha arvensisand Mentha piperitaand their antimicrobial activity against twelve Aeromonasspp. isolates from tambaquis (Colossoma macropomum), an important native farmed fish species in Brazil, were evaluated. The oils were characterized using gas chromatography and mass spectrometry (GC/MS) and their antimicrobial activity was evaluated through the microdilution method. The essential oils of these Menthaspecies mainly comprised oxygenated monoterpenes (97.1% for M. arvensisand 86.2% for M. piperita) and menthol was the major compound of these oils (86.1% for M. arvensisand 33.8% for M. piperita). It was confirmed that these oils had antimicrobial activity against 12 isolates of Aeromonasspp., with minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) ranging from 1,250 to 16,666.7 μg mL−1. Better antimicrobial activity was achieved by the M. arvensisessential oil.

AbstractThe objective of this study was to evaluate the antimicrobial activity of the essential oils from five Brazilian Piperspecies (Piper aduncum, Piper callosum, Piper hispidinervum, Piper hispidumand Piper marginatum) against strains of Aeromonas hydrophila, isolated from tambaqui (Colossoma macropomum), as well as their chemical composition. The oils were characterized by gas chromatography and mass spectrometry (GC/MS), and the major compounds identified were: dillapiole (80.7 %) for P. aduncum; safrole (67.0 %), methyl-eugenol (7.2 %) and β-pinene (6.6 %) for P. callosum; safrole (89.3 %) for P. hispidinervum; γ-terpinene (27.3 %), p-cymene (14.0 %) and α-terpinene (12.0 %) for P. hispidum; δ-3-carene (13.1 %), propiopiperone (8.0 %) and (E)-caryophyllene (6.8 %) for P. marginatum. The Brazilian Piperspecies evaluated in this study were able to inhibit the growth of the ten strains of A. hydrophila, with minimum inhibitory concentration (MIC) values ranging from 234.37 to 30,000 μg mL-1. The antimicrobial activity of Piperessential oils was considered strong for P. callosum, P. hispidinervum, P. hispidumand P. marginatum, with the exception of P. aduncumthat presented weak activity for all strains. This is the first record of antimicrobial activity of Piperessential oils against strains of A. hydrophilaisolated from tambaqui, suggesting the potential for use in the treatment of infections caused by this bacterium.

•Lippia sidoides, Ocimum gratissimum, and Zingiber officinaleEO was administered to tambaqui challenged with Aeromonas hydrophila.•Tambaqui fed diets supplemented with the aforementioned EO did not present significant differences in the growth parameters.•Fish fed with diets supplemented with 0.625 g/kg and 1.25 g/kg of L. sidoidesEO showed higher leukocyte respiratory activity.•Fish fed with a diet containing 0.625 g/kg of L. sidoidesEO presented higher survival rate after challenge.