Antibacterial Effect of a Short Peptide, VV18, from Calcineurin-A of Macrobrachium rosenbergii : Antibiofilm Agent Against Escherichia coli and a Bacterial Membrane Disruptor in Pseudomonas aeruginosa

We have reported the molecular function of Calcineurin A (Caln-A) identified from an earlier developed cDNA library of Macrobrachium rosenbergii ( Mr ). The antimicrobial function of Mr Caln-A was addressed through a short peptide (VV18). Mr Caln-A mRNA expression due to bacterial and viral stimulants indicates its potential antimicrobial involvement. In the screening assay, using 20 bacterial strains, VV18 showed effective antimicrobial activity against Aeromonas hydrophila MTCC 1739, Escherichia coli ATCC 9637 , Klebsiella pneumoniae ATCC 27736, Pseudomonas aeruginosa ATCC 2606 and Vibrio harveyi MTCC 7954. Based on this screening assay, a biofilm assay was performed on E. coli ATCC 9637, which indicated that the peptide VV18 inhibited the biofilm matrix of E. coli ATCC 9637. Further, the toxicity assay indicated that the peptide is not toxic at any of the tested concentrations (10–200 µM) against human blood erythrocytes and HEK293 primary cells. Flow cytometric observation revealed that the VV18 peptide disrupts the cell membrane of P. aeruginosa ATCC 2606 cells. The mechanism was further confirmed through scanning electron microscopy, wherein it has been visualised that P. aeruginosa ATCC 2606 bacterial membrane was disrupted by VV18. Mr Caln-A may be involved in the antimicrobial processes. VV18's function in the formation of antibiofilms and the degradation of bacterial membranes adds to the peptide's antimicrobial properties.