Antagonistic Interaction Between Beneficial and Pathogenic Bacteria Isolated from Ostreid Mollusks in Oyster Larvae (Crassostrea gigas): An In Vitro and In Vivo Evaluation

The Pacific oyster (Crassostrea gigas Thunberg, 1795) is a crucial species in global aquaculture; however, optimizing larval survival rates and ensuring high-quality seed production continue to pose significant challenges. Probiotics have been investigated as a potential solution throughout various stages of the production process. This study assessed strains of lactic acid bacteria (LAB) and pathogenic strains isolated from oysters. Notably, several LAB strains, particularly Lactobacillus plantarum 69Cr, demonstrated probiotic potential by inhibiting the growth of pathogens such as Vibrio proteolyticus. In Pacific oyster larvae, the L. plantarum 69Cr strain significantly improved survival, with an increase of over 80% compared to those exposed to the pathogen Staphylococcus pasteuri. These findings highlight the effectiveness of the L. plantarum 69Cr strain as a promising probiotic for protecting oyster larvae from pathogenic threats.