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Selected bacterial strains protect Artemia spp. from the pathogenic effects of Vibrio proteolyticus CW8T2
L Verschuere1, H Heang, G Criel
1Laboratory of Microbial Ecology and Technology, Department of Biochemical and Microbiological Technology, University of Ghent, B-9000 Ghent, Belgium.
Abstract:
In this study Vibrio proteolyticus CW8T2 has been identified as a virulent pathogen for Artemia spp. Its infection route has been visualized with transmission electron microscopy. The pathogen affected microvilli and gut epithelial cells, disrupted epithelial cell junctions, and reached the body cavity, where it devastated cells and tissues. In vivo antagonism tests showed that preemptive colonization of the culture water with nine selected bacterial strains protected Artemia juveniles against the pathogenic effects. Two categories of the selected strains could be distinguished: (i) strains providing total protection, as no mortality occurred 2 days after the experimental infection with V. proteolyticus CW8T2, with strain LVS8 as a representative, and (ii) strains providing partial protection, as significant but not total mortality was observed, with strain LVS2 as a representative. The growth of V. proteolyticus CW8T2 in the culture medium was slowed down in the presence of strains LVS2 and LVS8, but growth suppression was distinctly higher with LVS8 than with LVS2. It was striking that the strains that gave only partial protection against the pathogen in the in vivo antagonism test showed also a restricted capability to colonize the Artemia compared to the strains providing total protection. The in vivo antagonism tests and the filtrate experiments showed that probably no extracellular bacterial compounds were involved in the protective action but that the living cells were required to protect Artemia against V. proteolyticus CW8T2.
Insights
Selected bacterial strains protect Artemia juveniles from Vibrio proteolyticus CW8T2 infection. Living bacterial cells, not extracellular compounds, are crucial for this protective effect against the virulent pathogen.
Area of Science:
- Aquatic microbiology
- Animal pathology
- Biotechnology
Background:
- Vibrio proteolyticus CW8T2 is a virulent pathogen affecting Artemia spp.
- Understanding the infection route and protective mechanisms is vital for aquaculture.
Purpose of the Study:
- To identify protective bacterial strains against Vibrio proteolyticus CW8T2.
- To elucidate the mechanism of protection offered by these bacterial strains.
Main Methods:
- Transmission electron microscopy to visualize infection.
- In vivo antagonism tests with selected bacterial strains.
- Filtrate experiments to assess the role of extracellular compounds.
Main Results:
- Nine bacterial strains protected Artemia juveniles from V. proteolyticus CW8T2.
- Two categories of protection were observed: total (strain LVS8) and partial (strain LVS2).
- Protection correlated with bacterial colonization ability; living cells were required, not extracellular compounds.
Conclusions:
- Bacterial strains can effectively protect Artemia against V. proteolyticus CW8T2.
- The protective mechanism relies on direct interaction with living bacterial cells.
- This finding has implications for disease management in Artemia aquaculture.