6His-tatritin promotes antimicrobial defense via regulating immune ability and intestinal microbial community in grass carp (Ctenopharyngodon idella)

Antimicrobial peptides are small, cationic, and amphiphilic peptides found in most organisms, and many of these peptides have broad antimicrobial activity against Gram-negative,-positive bacteria and fungi. In the present study, a derivative of antimicrobial peptide Tatritin, 6His-Tatritin, was designed and expressed by Pichia pastoris using a constitutive vector pGAPZ alpha A with the promoter of pGAP. The 6His-Tatritin had a broad-spectrum antibacterial activity based on the Oxford cup method and the micro broth dilution test. In addition, to explore the role of 6His-Tatritin in vivo, grass carps (Ctenopharyngodon idellus) were infected with Aeromonas hydrophila after they were fed with 6His-Tatritin as feed additives for 28 days. The results revealed that 6His-Tatritin could significantly up-regulate the expression levels of Hepcidin, Leap-2b, Nrf-2, CuZn-SOD and LZM (P < 0.05). In addition, 6His-Tatritin could significantly reduce the mortality (P < 0.05) and the intestinal injury of grass carps infected with bacteria. The 16S sequencing analysis showed that the structure of microbial community in intestine of fish was more diversified compared with control after treatment with 6His-Tatritin. In summary, the peptide of 6His-Tatritin could promote antimicrobial defense via regulating immune ability and intestinal microbial community in grass carp. This study provides an effective method and approach for the application of antimicrobial peptide Tatritin in aquaculture, and also provides insights into the function of antimicrobial peptides in immunity against pathogens in fish.

Automated summary

In this study, a derivative of antimicrobial peptide Tatritin called 6His-Tatritin was designed and expressed. It showed broad-spectrum antibacterial activity and could regulate immune ability and intestinal microbial community in grass carp. This research provides a method for the application of Tatritin in aquaculture and offers insights into the function of antimicrobial peptides in fish immunity against pathogens.