Abstract
Vibriosis, caused by Vibrio strains, is an important bacterial disease and capable of causing significant high mortality in aquatic animals. Essential oils (EOs) have been considered as an alternative approach for the treatment of aquatic bacterial diseases. In this study, we evaluated the antibacterial activity of essential oils (n = 22) or essential oil components (EOCs, n = 12) against Vibrio strains belonging to the harveyi clade. It was verified by three different approaches, e.g., (i) a bacterial growth assay, comparing Vibrio growth with or without EO(C)s at various concentrations; (ii) a vapor-phase-mediated susceptibility assay, comparing the effect of EO(C)s on bacterial growth through the vapor phase; and (iii) a quorum sensing-inhibitory assay, based on specific inhibition of quorum sensing-regulated bioluminescence. The results showed that, in the bacterial growth assay, EOs of Melaleuca alternifolia and Litsea citrata at 0.0001%, Eucalyptus citriodora at 0.01% can inhibit the growth of Vibrio campbellii BB120. These EOs can also prevent the growth of V. parahaemolyticus strains but need to be present at a higher concentration (0.1%). Moreover, in the vapor-phase-mediated susceptibility assay, EOs of M. alternifolia, L. citrata and E. citriodora can inhibit the growth of V. campbellii BB120 through their vapor phase. However, V. parahaemolyticus strains (CAIM170, LMG2850 and MO904) cannot be inhibited by these EOs. Additionally, in the quorum sensing-inhibitory assay, EOs of Mentha pulegium, Cuminum cyminum, Zingiber officinalis, and E. citriodora, all at 0.001%, have quorum sensing-inhibitory activity in V. campbellii BB120. Taken together, our study provides substantial evidence that usage of the major components, individually or in combination, of the tested commercial EOs (extracted from M. alternifolia, L. citrata, and E. citriodora) could be a promising approach to control V. campbellii BB120.
Highlights
Vibriosis is considered an important disease hampering the aquaculture sector, resulting in serious economic losses worldwide [1]
Our study provides substantial evidence that usage of the major components, individually or in combination, of the tested commercial Essential oils (EOs) could be a promising approach to control V. campbellii BB120
V. campbellii BB120 is the causative agent of luminescent vibriosis and reported to infect brine shrimp (Artemia franciscana) and giant river prawn (Macrobrachium rosenbergii), and its virulence is likely contributed by quorum sensing regulatory gene, transmembrane transcription regulator, metalloprotease, chitinase, and hemolysin [7,8]
Summary
Vibriosis is considered an important disease hampering the aquaculture sector, resulting in serious economic losses worldwide [1]. The Gram-negative marine bacteria, Vibrio spp. are important aquatic pathogens and capable of causing vibriosis and several other important diseases. This disease, vibriosis has been reported from 48 species of aquatic animals leading to significant high mortality [2]. Shrimps are a major marine product, with high economic value, but their commercial production has been threatened by bacterial or viral infections, especially by Vibrio contamination [1]; for instance, V. parahaemolyticus MO904 is a high-level pathogen bacterium encoding VPAHPND toxins (PirAVp/PirBVp) causing acute hepatopancreatic necrosis disease (AHPND) in shrimp [5,6]. V. parahaemolyticus LMG2850 is high-level pathogenic bacterium widely associated with foodborne infection and outbreaks linked to seafood, causing vomiting and diarrhea [9], encoding the thermostable direct hemolysin-related hemolysin (trh) gene
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