Papain: an antimicrobial enzyme of Papaya latex inhibits the production of biofilm and disrupts pre-formed biofilm matrix of Pseudomonas aeruginosa.

In this study, papain (also known as papaya proteinase I; EC 3.4.22.2), a cysteine protease derived from Carica papaya, a tropical fruit cultivated worldwide in tropical and subtropical regions, is used. Biofilm-forming Pseudomonas aeruginosa poses a major therapeutic challenge due to its heightened antibiotic tolerance and ability to persist in chronic infections. This study reports that the enzyme papain inhibits approximately 80% of Pseudomonas aeruginosa biofilm production at a sub-MIC dose of 80 µg/mL, along with reduced levels of pathogenic molecules, including 87% of total acyl-homoserine lactones, 83% of LasA, 85% of LasB, 89% of pyocyanin, 87% of rhamnolipids, and 86% of exoprotease activity. FE-SEM results have confirmed the absence of new biofilm and the disruption of preformed biofilm due to papain treatment of the bacterial cells. AFM results also indicate the lowering of height in papain treated bacterial biofilm. By targeting both preformed and newly formed biofilms, papain offers a promising, sustainable therapeutic strategy derived from a plant source to manage biofilm-associated infections, addressing a critical gap in current antimicrobial approaches. Therefore, papain, a natural antimicrobial protein, has the potential to eradicate biofilms at infected sites.