Toxicity evaluation and antimicrobial activity of purified pyocyanin from pseudomonas aeruginosa

Abstract

Pigments from microbial sources considered a promising approach in food industry applications as a food colorant and biopreservatives agents. This study aims to evaluate the antimicrobial activity of purified pyocyanin against foodborne pathogens and study the safety of pyocyanin by toxicity determination. Purification and structure elucidation of pyocyanin was carried out using a UV-Vis spectrophotometer, Fourier Transform Infra-Red Spectroscopy (FTIR) and GC-MS analysis. Pyocyanin showed antibacterial activity against 9 species of foodborne pathogenic bacteria with a zone of inhibition from 10.8 to 22.6 mm, and minimum inhibitory concentration (MIC) value ranged between 33.3 to 233.3 µg ml-1. Also, pyocyanin has antifungal activity against 10 mycotoxigenic fungi strains with inhibition zone value ranged from 7.0 to 17.6 mm and MIC value from 58.3 to 250 µg ml-1. No toxicity was observed on shrimp nauplii up to 50 µg ml-1 for 12 and 24 h of exposure and up to 100 µg ml-1 for 12 h. Also, no toxicity was recorded with pyocyanin using mouse bioassay up to 750 µg ml-1, while 1000 µg ml-1 observed toxicity equal to 3.28 MU (mouse unit). Pyocyanin had antimicrobial activity against a wide range of foodborne pathogenic bacteria and mycotoxigenic fungi. Consequently, pyocyanin can be used as a cheap and safe source in the food industry and pharmaceutical applications.