Antibacterial activity of bioactive metabolites from Pleurotus pulmonarius against selected isolates

Abstract

Submerged fermentation of Pleurotus pulmonarius was carried out for over a period of 7 
days in order to obtain phytotoxic metabolites. Separation of the metabolites was carried 
out using standard methods (mycelia, aqueous, and organic extracts). The antibacterial 
activity of the metabolites from the three extracts was investigated against Escherichia 
coli ST2747, Klebsiella pneumonia strain PMK1, Salmonella enterica subsp. enterica sero
var typhimurium strain 08-1736, and Pseudomonas aeruginosa VRFPA04 using agar-well 
diffusion technique. Phytochemical analysis was determined qualitatively and minimum 
inhibitory and minimum bactericidal concentrations were determined by plate assays. 
Standard antibiotics were used to compare the antibacterial activity of metabolites using 
the disk diffusion methods. The antimicrobial assay revealed that only the mycelial extract 
exhibited activity against the selected test strains. Phytochemical screening showed the 
presences of three phytoconstituents which include alkaloids, flavonoids, saponins, tan
nin, steroids, glycosides, phenols, and anthraquinones at varying concentrations in the 
mycelia extract. The highest zone of inhibition of the test organism was recorded in K. 
pneumoniae, while the least was detected in P. aeruginosa. Phytotoxic metabolites 
obtained through submerged fermentation have been discovered to be antagonistic 
against pathogenic organisms which could be carried out to develop antimicrobial drugs 
to combat the menace of drug resistance as witnessed in some synthetic drugs.