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Plant essential oils against A eromonas hydrophila : in vitro activity and their use in experimentally infected fish
Author(s) -
Sutili F.J.,
Lima Silva L.,
Gressler L.T.,
Gressler L.T.,
Battisti E.K.,
Heinzmann B.M.,
Vargas A.C.,
Baldisserotto B.
Publication year - 2015
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/jam.12812
Subject(s) - catfish , aeromonas hydrophila , biology , clarias gariepinus , ocimum , aeromonas , tilapia , microbiology and biotechnology , antibacterial activity , fish <actinopterygii> , traditional medicine , food science , bacteria , botany , medicine , fishery , genetics
Aims The aims of this study were to investigate the in vitro antibacterial activity of the essential oils (EOs) of Hesperozygis ringens (HREO), popularly known as ‘espanta‐pulga’ and two different species of basil, Ocimum gratissimum (OGEO) and Ocimum americanum (OAEO), as well as, the potential of these products to be used in silver catfish ( Rhamdia quelen ) infected with Aeromonas hydrophila . Methods and Results OGEO and HREO showed better antibacterial activity in vitro . Subinhibitory concentrations of all EOs inhibited haemolysis caused by Aer. hydrophila in fish erythrocytes (100% reduction for OAEO at 100 μ g ml −1 and more than 90% for HREO and OGEO at 150 μ g ml −1 ). However, OAEO and HREO showed the best survival results (75 and 70% respectively) after their use as treatment (therapeutic baths—1 h daily/5 days) in silver catfish experimentally infected with Aer. hydrophila . A second in vivo assay using healthy fish was conducted to verify the potential of the EOs (preventive baths—1 h daily/5 days) to promote fish survival. Fish exposed to HREO and OAEO and their diluent (ethanol) showed significant lower haematocrit values and higher complement system activity compared to control. Plasma cortisol level was significantly higher in the groups exposed to both EOs. There was no significant difference in survival of silver catfish challenged with Aer. hydrophila after preventive baths with HREO, OAEO and control group. Conclusions All tested EOs showed in vitro antibacterial properties against Aer. hydrophila and HREO and OAEO showed potential to be used in the treatment of infected fish. Significance and Impact of the Study These products can be used in aquaculture as therapeutic and prophylactic agents against fish pathogens, with antimicrobial and/or immunostimulant properties.