This study evaluated the anti-virulence effect of AuraAqua (Aq), a natural mixture of organic acids, against Pseudomonas. fluorescens. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Aq against P. fluorescens were 0.5% and 1% (v/v), respectively. Growth curve analysis confirmed concentration-dependent inhibition of planktonic growth, while sub-inhibitory Aq (0.25%; 1/2 MIC) significantly reduced biofilm formation. Rhodamine-based assays revealed membrane depolarisation at both 0.25% and 0.5% Aq, with decreased intracellular protein levels, indicating impaired membrane integrity under the tested conditions. In fibronectin adherence assays, the presence of Aq during bacterial contact markedly reduced adherence, whereas short pre-treatment alone produced limited, non-persistent effects, suggesting that continuous exposure is required to interfere with host matrix binding. Supernatants and lysates from Aq-exposed P. fluorescens induced lower extracellular protease activity in a concentration-dependent manner and mitigated P. fluorescens-induced cytotoxicity in primary shrimp (SGP) and tilapia (TGP) gut cells, as measured by lactate dehydrogenase (LDH) release after exposure to bacterial supernatants and lysates. Aq treatment was associated with decreased P. fluorescens internalisation into SGP and TGP cells. Collectively, these data show that Aq exerts multi-target inhibitory and virulence-attenuating effects on P. fluorescens, supporting its potential use in aquaculture environments.
Bundurus et al. (Sat,) studied this question.