Pyocyanin: Process optimization and evaluation of its antimicrobial activity

Abstract

In present study Pseudomonas aeruginosa with potential of pyocyanin pigment production was screened and its efficacy was estimated. The selected potent strain was identified up to species level by morphological, biochemical and molecular methods. The produced pigment was qualitatively and quantitatively characterized by using spectrophotometric methods. Lambda max value of the extracted pigment was found to be 320 and 520nm at alkaline and acidic conditions respectively. The conditions for growth and production of pyocyanin were optimized by classical (one parameter at a time) method in which media type and composition, physical parameters like pH, incubation temperature and salt concentration were studied. Maximum yield was obtained from the nutrient broth containing 1% glycerol at pH 7, Temperature 37oC and salt concentration 0.5 %. Silica gel column chromatography was effectively used for purification of extracted pyocyanin. The antimicrobial activity of the pyocyanin was evaluated against human pathogenic bacteria S. aureus, E. coli, Salmonella sp., Klebsiella sp., Proteus sp. and phytopathogenic fungi Cerratocystis caradum, Sclerotium sp., Altenaria alternatum, Aspergillus asporagus, Aspergillus niger and Penicillium sp. MIC of the pyocyanin against Staphylococcus aureus and Klebsiella sp. was found 12 µg/L and 8 µg/L respectively. The study showed that Gram negative bacteria are more sensitive to the pyocyanin than Gram positive. The pyocyanin also showed potent antifungal activity against Cerratocystis caradum, Sclerotium sp. and Altenaria alternatum.