A New Strategy to Prevent Emerging Lactococcus garvieae Infections by Using Organic Acids as Antimicrobials In Vitro...

Area of Science:

• Aquaculture
• Fish Pathology
• Microbiology

Background:

• Aquaculture expansion faces challenges in sustainable practices due to increasing global demand for animal protein.
• Lactococcus garvieae (L. garvieae) causes significant issues in fish health, necessitating effective control strategies.
• Antibiotic use in aquaculture raises concerns regarding environmental impact and resistance development.

Purpose of the Study:

• To evaluate the efficacy of an organic acid mixture (Aq) in mitigating L. garvieae virulence.
• To investigate Aq's impact on bacterial virulence factors such as EPS production, biofilm, and haemolysis.
• To assess Aq's effects on host pathogenicity, including epithelial cell adherence, haemolysis, and inflammatory responses.

Main Methods:

• Tested Aq's inhibitory effect on L. garvieae growth and virulence factors (EPS, biofilm).
• Assessed Aq's impact on bacterial adherence to CHSE-214 cells and red blood cell lysis.
• Measured changes in host proinflammatory cytokine expression (IL-1β, IL-8) following Aq treatment.

Main Results:

• Aq significantly inhibited L. garvieae growth at 0.125%, suppressed EPS and haemolytic gene expression, and reduced biofilm formation.
• Aq decreased bacterial adherence to fish epithelial cells and attenuated red blood cell lysis.
• Aq modulated host immune responses by lowering IL-1β and IL-8 expression, reducing inflammation.

Conclusions:

• Aq acts by inhibiting L. garvieae adhesion, reducing EPS production, and downregulating virulence genes.
• Aq mitigates L. garvieae pathogenicity by preventing epithelial barrier breaches and red blood cell lysis.
• Aq shows potential as a non-antibiotic alternative for controlling piscine lactococcosis in aquaculture.