Antibiofilm compounds from Streptomyces Labedae 20PM improves survival of and prophylactic effect of Nile tilapia (Oreochromis niloticus) challenged with Aeromonas hydrophila

In this study, we investigated the anti-quorum-sensing and biofilm disruption activities of bacterial extracts from Streptomyces labedae 20PM against A. hydrophila (in vitro and in vivo). Quantitative analysis showed that the crude extract had stronger anti-quorum-sensing activity in biofilms than the supernatant. Toxicity assessments indicated that both the supernatant and crude extract were non-toxic (24-hour LC₅₀ >1000 ppm). GC-MS analysis identified 2-pentylpiperidine and (S)-2-propylpiperidine as the dominant compounds in the supernatant and crude extract, respectively. In vivo assays, including blood analyses and survival confirmed that incorporating the crude extract and supernatant into fish feed significantly contributed to the prevention and treatment of A. hydrophila infections in Nile tilapia. These findings suggest that the bioactive compounds derived from S. labedae 20PM have strong potential as natural agents for controlling A. hydrophila biofilm formation in aquaculture systems, offering a novel approach to mitigating bacterial infections.