Study On The Antimicrobial Mechanism And Application Of Skin Mucus Extract From Channa Argus

Fish live in a microbe-rich environment and are constantly exposed to high concentrations of pathogenic microbes.Therefore,they must have excellent biological functions and defenses ability to protect themselves from the abundant microbial load in the aquatic environment.In recent years,a variety of natural endogenous antimicrobial peptides(AMPs)have been obtained and identified from fish,some of which are unique to fish.The mucosal surface of fish plays a crucial role in the first line of defense against invading pathogens.Studies have shown that epidermal mucus is rich in antibacterial active ingredients that help to prevent colonization of bacterial and fungal.In this paper,the skin mucus of Channa argus was used as the experimental material to extract antimicrobial active substances,and the antimicrobial mechanism of the skin mucus extract was studied by non-targeted metabolomics.Meanwhile,we used Channa argus fillets as experimental materials to explore the effect of the skin mucus extract on the quality changes of fillets during storage.The results will provide theoretical basis and technical support for the high-value utilization of by-products from the processing of Channa argus.The main finding are as follows:1.Extraction of antimicrobial substances from skin mucus of Channa argus and evaluation of antimicrobial activityEscherichia coli and Staphylococcus aureus were used as test strains to detect the inhibitory effect of antibacterial active substances extracted from skin mucus of Channa argus.The results showed that the skin mucus extract had a good antibacterial activity against the test strains and could slow down the growth rate of the strain effectively.Scanning electron microscopy showed that the cell membrane of the treated cells had different degrees of cell membrane damage,most of the cells had wrinkled and collapsed surface,and the cell membrane was completely broken and the morphology was seriously damaged under high concentration.Cell membrane damage experiment showed that the skin mucus extract could increase the permeability of bacterial cell membrane and destroy the integrity of cell membrane.2.The antibacterial mechanism of the skin mucus extract of Channa argus was studied by non-targeted metabolomicsNon-targeted metabolomics was used as the research method to compare the changed of metabolite spectra of the tested strains before and after the treatment of the skin mucus extract,so as to further explore the antibacterial mechanism at the molecular level.The results showed that the metabolite spectra of the tested strains changed significantly before and after treatment,and their metabolic pathways were disturbed to varying degrees.The main metabolic pathways of differential metabolite enrichment in Escherichia coli are amino acid metabolism,tricarboxylic acid cycle,glycerolipid metabolism,pyrimidine and purine metabolism,respectively.The differential metabolites in Staphylococcus aureus were mainly concentrated in amino acid biosynthesis and metabolism,oxidative phosphorylation,glutathione metabolism and caramyl-t RNA biosynthesis and metabolism pathways.3.The effect of the skin mucus extract of Channa argus on the quality of Channa argus fillets was investigated during storage.The conventional method was used to evaluate the effect of the skin mucus extract on the preservation of fish fillets.The results showed the Channa Argus Mucus Extract(CAME)treatment group could slow down p H,microorganisms,electrical conductivity,water holding capacity,malondialdehyde and volatile base nitrogen compared with the control group.Furthermore,it can also delay the change of color difference and texture characteristics of the fish fillet,which can effectively slow down the spoilage of the fish fillet during the cold storage process and extend the shelf life for 3 days.