Extraction, Purification, characterization and antibacterial activity of phenoloxidase extracted from the Sea Squid

Serious morbidity and mortality resulted from the failure of traditional antibiotic treatment due to the rise of methicillin-resistant Staphylococcus aureus (MRSA). One possible mechanism for antibiotic resistance in S. aureus is the production of biofilms. Essential regulatory proteins for the development of S. aureus biofilms are SarA, aur and nus. In this work, we isolated and refined phenoloxidase and tested it against S. aureus to determine its antibiofilm capabilities. Using L-dihydroxyphenylalanine (L-DOPA) as the particular substrate, phenoloxidase (PO) from sea squid ink sacs was purified ion-exchange chromatography, and its biochemical and enzymatic characteristics were described. We assessed the MIC, eDNA inhibition, and gene expression of the purified PO as an antibacterial agent against S. aureus. Comparing the PO’s MIC to the positive control, we discovered that it was 61μg/ml, a considerable difference. Both eDNA and extracellular polymer material (EPS) were inhibited. We discovered that whereas other regulatory proteins like nuc and sarA were increased, aur was downregulated based on the results of the real-time PCR. This validates the PO’s possible role as an antibiofilm agent. To sum up, this study’s findings demonstrated PO’s anti-biofilm action on MRSA.