Artemia is an important aquaculture feed organism , widely used in hatcheries . However, Artemia is prone to carrying pathogenic microorganisms such as Vibrio, posing potential threats to the breeding and cultivation of aquaculture species. With the rapid development of the aquaculture industry, there is an urgent need to enhance the growth and health of Artemia while reducing its pathogen load. Organic acids, such as non anoic acid, have been applied in aquaculture and livestock farming because they promote animal growth, inhibit pathogenic microorganisms, and enhance animal immunity. In this study, nonanoic acid was combined with chitosan and added to the rearing water of Artemia to investigate its effects on the microbial community composition and growth performance of Artemia franciscana. The experiment showed that the relative abundance of Vibrio carried by Artemia adults decreased by 46.73% compared to the control , and the expression of lipogenesis gene (acaca) increased and was further confirmed by quantitative real-time PCR (qRT-PCR).
Briefly, nonanoic acid and chitosan were mixed in a 60:1 (μM /g) ratio to form particles. The cysts were treated with mixed particles then hatched and cultured for 7 days. After hatching, all s amples were collected on day 2 and 7 for 16S rRNA sequencing and transcriptome analysis , respectively.
In Artemia nauplius samples， species of the genus Psychrobacter accounted for 54.8%, which was significantly (P＜0.05) higher than the control (Fig. 1A) . I n adult Artemia , Vibrio accounted for only 10.35%, significantly (P＜0.05) lower than the control (56.53%) (Fig. 1B). Transcriptome analysis revealed 3182 differentially expressed genes (DEGs) associated with 337 pathways, including growth- and immune-related pathways such as AMPK, PI3K-Akt , mT OR and Notch signaling pathway (Fig. 2). Additionally, genes related to innate immunity (hsp90) and growth (pik3ca , mtor , pck , and acaca) showed increased expression.
In the experimental group, qRT-PCR analysis confirmed that acaca expression was markedly higher than in the control.