Characterization of Novel Antimicrobial Peptides from the Epidermis of Clarias batrachus Catfish

In this study, an antimicrobial protein (AMP) from the epidermis of catfish ( Clarias batrachus ) was purified and characterized for its molecular and antimicrobial properties. The crude epidermal extract was subjected to precipitation of proteins using 70% ammonium sulphate saturation followed by dialysis and protein separation by reverse phase ultra fast liquid chromotography (UFLC) using the C 18 column. The active peptides obtained from fractions 1, 2, and 3 were screened for antimicrobial activity against different bacterial pathogens with a minimum 5 mg/ml inhibitory concentration. An active fraction with a retention time (RT) of 27.069 from the UFLC chromatogram exhibited significant antimicrobial activity against broad-spectrum bacterial and fungal organisms, including multidrug-resistant clinical isolates. The RT 27.069, identified as cationic AMP of fraction-3, has a molecular weight of 25 kDa as determined by MALDI-TOF mass spectrometry. Further studies by Mascot search and BLAST analysis using the partial sequence of AMP showed that the protein has high homologs to pleurocidin-like peptide ( Pl p) from a fish Pleuronectus americanus. Moreover, the identified AMP is a cationic peptide with a good stability index, having a score of 31.50 predicted by the ProtParam. Therefore, the identified antimicrobial peptide ( Plp ) indicates that this cost-effective natural substance obtained from fish could potentially be used as a treatment for several bacterial and fungal infections in humans.