Crustaceans have a powerful non-specific immune mechanism that responds to pathogen invasion andtogether with cellular responses, generates powerful humoral factors such as antimicrobial peptides.Crustins are a diverse class of antimicrobial peptides that are expressed by the circulating haemocytesof crustaceans. Several isoforms of this molecule are reported and in this study, one isoform from theblack tiger shrimp, Penaeus monodon was cloned and expressed in Escherichia coli SG 13009. The purifiedrecombinant crustin peptide had a molecular weight of 22 kDa and exhibited potent anti-bacterial activityin vitro against several Gram positive and Gram negative bacteria that included pathogens of aquaticanimals and humans. The recombinant crustin showed a minimal inhibitory concentration of 0.5 g ml−1against the vibrio pathogens of shrimp, which suggests its promise for application in aquaculture.© 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-NDlicense (http://creativecommons.org/licenses/by-nc-nd/4.0/).