Effects of Pyropia yezoensis eYnzymatic hydrolysate on the growth and immune regulation of the zebrafish

The supplemental effect of Pyropia yezoensis enzymatic hydrolysate (PYE) in fish diet was evaluated in zebrafish (Danio rerio) model. A basal diet supplemented with PYE at 0, 0.1, 1.0 and 2.0% were fed to one-month old zebrafish for 6 weeks, its growth performance and immunity index were evaluated. The increase in weight gain was significantly higher when supplementary 1% PYE which shows a positive effect on growth performance of zebrafish. In addition, crude protein content of fish body was increased in all PYE supplemental groups. The innate immune responses and activity of digestive enzymes in zebrafish were enhanced with dietary supplementation of PYE additives. Compared with the control group, lysozyme (LYZ) and interleukin-10 (IL-10) content in zebrafish intestines were up-regulated in groups fed with 0.1% and 1% PYE. The mRNA expression levels of LYZ and IL-10 in zebrafish intestines were consistent with ELISA results. The content of tumor necrosis factor (TNF-alpha) reduced in 1% and 2% PYE groups. Furthermore, PYE down-regulated the relative abundance of pathogenic bacteria (Aeromonadaceae) and up-regulated the relative abundance of fish probiotics (Brevibacillus) in intestinal flora. The findings in this study indicated that PYE supplementation in diet could promote growth, improve immunity and regulate intestinal flora, which made PYE considered as an potential aquatic additive.

Automated summary

This study evaluated the supplemental effect of Pyropia yezoensis enzymatic hydrolysate (PYE) in fish diet using zebrafish as a model. The results showed that adding 1% PYE to the diet significantly improved the growth performance of zebrafish and increased the crude protein content of their bodies. Moreover, PYE supplementation enhanced the innate immune responses and activity of digestive enzymes in zebrafish, as well as regulating the intestinal flora. These findings suggest that PYE could potentially be used as an aquatic additive.