Purification And Antimicrobial Mechanisms Of Catfish Epidermal Mucus Antimicrobial Peptides

Epidermal mucus antibacterial peptides are the first barrier to fish autoimmunity.This study focused on the separation and purification of catfish epidermal mucus antibacterial peptides(CEMP),researched the antibacterial mechanisms,and application effect on fish fillets storage.Catfish epidermal mucus antibacterial peptides(CEMP)were isolated and purified from live health catfish epidermal mucus.The mucus was extracted by agent,the solution containing sodium acetate trihydrate(0.2 M),Triton X-100(0.2%)and benzylsulfonyl fluoride(1 mM).After centrifuging,the supernatant ran through SPE(C18,RP-HPLC,and HPLC successively.Bioactive CEMP were obtained finally.The amino acid sequences of CEMP were identified as RLKEKNKA(759.5 U),RIVELTLPRVSVRL(1381.9 U),KQEIILKF(743.5 U),and RQIKIXRR(786.5 U).The antibacterial mechanisms of CEMP against Shewanella putrefacients,Pseudomonas fluorescens,and Bacillus cereus were investigated in this study.CEMP could decrease bacterial growth rate,change microbial morphology,inhibit activity of Na+K+-ATP enzyme and AKP enzyme,damage bacterial cell inner and outer membrane,change bacteria total protein and membrane protein.The solution of catfish epidermal mucus antibacterial peptide(0.5%,w/v)was evaluated on the quality of grass carp fillets storage at 4?.Bacteriological(total viable counts(TVC),Shewanella putrefacients,Pseudomonas fluorescens),physicochemical(pH,total volatile basic nitrogen(TVB-N),K value,surface color,texture profiles),and the volatile odorous compounds were all improved,except water distribution within muscle.Comparing with protamine,CEMP was more durable to inhabit TVC and more effective on inhibiting the growth of TVB-N value,K value and the count of Pseudomonas fluorescens.CEMP was less effective on restraining the production of Sulphur-organic(H2S)group substances.