Peptidome of peptide fractions generated from Spirulina biomass: Antimicrobial activity and its application as a feed additive for shrimp larvae

Spirulina biomass is a widely used feed additive for Litopenaeus vannamei larvae and postlarvae, however peptides generated via pepsin digestion of the biomass, which resembles biomass digestion in the vannamei intestine, have not been explored. In the present study, peptidome analysis of protein hydrolysate and Spirulina biomass fractions partially purified via size exclusion methods was carried out by using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The bioactivity of the peptides obtained was categorized and predicted using SmartBioPep, an AI-based peptide analytical platform. The bioactivity tests were then performed. The results of the growth performance of shrimp larvae revealed a 20 % increase in the survival rate and a 24 h decrease in the phase transition time compared with those of the control when the peptide fraction MWC30K was present in the diet. Moreover, two orders of magnitude fewer Vibrio spp. cells were found in the cultivation seawater at the end of the experiment when the MWC30K fraction was fed, and the MWC3K fraction presented a very effective MIC of 32 ppm for Vibrio parahaemolyticus . The data revealed that the MWC30K fraction has both antimicrobial and immunoboosting activities, probably by directly inducing the innate immunity of the larvae or possibly by acting as a prebiotic for the gut microbiota, which then synthesizes secondary metabolites that subsequently increase innate immunity. • Spirulina biomass used as protein source for bioactive peptide production. • Peptide products contained antimicrobial and immunoboosting activities. • The peptide MWC30K supplemented diet exhibits the best vannamei-growth performance. • The MWC3K fraction represents 32 ppm MIC against V. parahaemolyticus .