Biofilm Killing Effects of Chromolaena odorata Extracts against Pseudomonas aeruginosa

摘要

Chromolaena odorata is known to possess antimicrobial effects against a wide range of microorganisms including Pseudomonas aeruginosa . However, the inhibitory effects of Chromolaena odorata extracts against the biofilm growth mode of Pseudomonas aeruginosa remain uncertain. Therefore, this study was carried out to determine the antibiofilm activity of Chromolaena odorata extracts against Pseudomonas aeruginosa under aerobic and anaerobic conditions. Phytochemical screening using gas chromatography mass spectrometry revealed the major constituent in both Chromolaena odorata chloroform and ethanolic extract s, namely germacrene D. All microbial tests were carried out under aerobic and anaerobic conditions. Based on microbroth dilution assay performed, oxygen level did not show any effect towards the minimum inhibitory concentration and minimum bactericidal concentration of Chromolaena odorata extracts against Pseudomonas aeruginosa . However, antibacterial susceptibility test showed that the size of inhibition zones of Chromolaena odorata extracts against Pseudomonas aeruginosa were slightly different between the aerobic and anaerobic conditions. Colony forming unit counting of biofilm cells demonstrated that Chromolaena odorata chloroform extract had greater antibiofilm activity against Pseudomonas aeruginosa as compared to Chromolaena odorata ethanolic extract under aerobic condition. In contrast, Chromolaena odorata ethanolic extract showed greater antibiofilm activity against Pseudomonas aeruginosa biofilm than Chromolaena odorata chloroform extract in the absence of oxygen. Furthermore, treatment of both Chromolaena odorata chloroform and ethanolic extract s resulted in changes in bio chemical composition of Pseudomonas aeruginosa biofilm extracellular matrixes under both experimental conditions, as indicated by variation in the infrared spectra in the region between 1700 and 900 cm^-1. We conclude that the antibiofilm activities of Chromolaena odorata extracts depend on solvent extraction method and oxygen level. The findings from this study would improve the existing antimicrobial treatment plan to combat facultative anaerobic Pseudomonas aeruginosa biofilm.