Pseudomonas juntendi MaLMAid0250 Suppresses Vibrio in Artemia and Enhances Survival of Vibrio-Challenged Black Scraper (Thamnaconus modestus).

In the aquaculture industry, the survival rate of fish and shrimp larvae is critical, as various Vibrio species can cause disease and mortality. Larvae are often fed on live feed, such as Artemia, which can provide nutrients and probiotics, but may also act as a carrier for pathogens. In this study, we assessed the anti-Vibrio efficacy of Pseudomonas juntendi MaLMAid0250, isolated from Artemia franciscana rearing water, against V. alginolyticus, V. anguillarum, V. harveyi, V. parahaemolyticus, and V. proteolyticus. The results showed that P. juntendi MaLMAid0250 belongs to the P. putida group and exhibited 97.99% average nucleotide identity with the P. juntendi type strain. A significant quantitative inhibitory effect was observed in Artemia at specific concentrations against all Vibrio species, and supernatant antibacterial activity was observed against Vibrio species, except V. anguillarum. Furthermore, survival rate analysis of black scraper Thamnaconus modestus revealed that groups fed Artemia co-loaded with MaLMAid0250 and V. harveyi showed significantly improved survival compared to groups fed Vibrio-only-loaded Artemia. Gut microbiota analysis further revealed compositional shifts associated with improved survival outcomes. These results suggest that P. juntendi MaLMAid0250, a probiotic derived from Artemia rearing water, exhibits broad-spectrum inhibitory activity against Vibrio species and improves fish survival rate.