Antimicrobial properties of metabolites produced by Klebsiella aerogenes and Bacillus pumilus
Abstract
Natural organic compounds produced by microorganisms are important screening target for a variety of bioactive substances. Some bacteria which are normally susceptible are daily reverting to resistant forms. On this premise, the search for new and potent antimicrobial substances especially, those that will be able to check the development and/or resurgence of
resistant strains is the basis for this work. The aim of this study was to isolate and characterize those organisms that can produce antimicrobial metabolites of fatty acid origin, its effect, and investigate the bacteriocidal activities of the metabolites by determining the rate of killing of the test agents. Metabolites obtained from Klebsiella aerogenes (CWS) and Bacillus pumilus (IWS) were found to exhibit anti-microbial properties against a wide range of organisms. The metabolites, CWS and IWS, resulted in diameters of zone of inhibition of 13 and 17 mm when tested against Pseudomonas aeruginosa, and 17 and 18 mm when tested against Bacillus subtilis respectively. The bacteriocidal activity showed that a concentration of 0.15 mg ml -1 of Klebsiella aerogenes metabolites reduced the population of Bacillus subtilis from 2.4 x 10 7 to 1.3 x 10 7 cfu ml -1 at 10 min incubation period. There was no significant difference in the population density of Bacillus subtilis after 10 min exposure to 0.15 mg ml -1 of Bacillus pumilus metabolites (4.0 x 10 7 to 3.5 x 10 7 cfu ml -1 ). A similar trend was obtained for Pseudomonas aeruginosa with both metabolites. A low minimum inhibitory concentration (MIC) of 0.05 mg ml -1 for (CWS) and 0.05 and 5.0 mg ml -1 for (IWS) in Pseudomonas aeruginosa and Bacillus subtilis were obtained respectively. The infra-red spectral analysis (IR) of the metabolites revealed several functional groups like carboxylic acid, aldehyde and ester carbonyl. A component of each
of the metabolites corresponded to 10-hydroxyoctadecanoic acid R f value of 0.35. It can be concluded that the metabolites produced by Klebsiella aerogenes and Bacillus pumilus can serve as effective antimicrobial agents.
resistant strains is the basis for this work. The aim of this study was to isolate and characterize those organisms that can produce antimicrobial metabolites of fatty acid origin, its effect, and investigate the bacteriocidal activities of the metabolites by determining the rate of killing of the test agents. Metabolites obtained from Klebsiella aerogenes (CWS) and Bacillus pumilus (IWS) were found to exhibit anti-microbial properties against a wide range of organisms. The metabolites, CWS and IWS, resulted in diameters of zone of inhibition of 13 and 17 mm when tested against Pseudomonas aeruginosa, and 17 and 18 mm when tested against Bacillus subtilis respectively. The bacteriocidal activity showed that a concentration of 0.15 mg ml -1 of Klebsiella aerogenes metabolites reduced the population of Bacillus subtilis from 2.4 x 10 7 to 1.3 x 10 7 cfu ml -1 at 10 min incubation period. There was no significant difference in the population density of Bacillus subtilis after 10 min exposure to 0.15 mg ml -1 of Bacillus pumilus metabolites (4.0 x 10 7 to 3.5 x 10 7 cfu ml -1 ). A similar trend was obtained for Pseudomonas aeruginosa with both metabolites. A low minimum inhibitory concentration (MIC) of 0.05 mg ml -1 for (CWS) and 0.05 and 5.0 mg ml -1 for (IWS) in Pseudomonas aeruginosa and Bacillus subtilis were obtained respectively. The infra-red spectral analysis (IR) of the metabolites revealed several functional groups like carboxylic acid, aldehyde and ester carbonyl. A component of each
of the metabolites corresponded to 10-hydroxyoctadecanoic acid R f value of 0.35. It can be concluded that the metabolites produced by Klebsiella aerogenes and Bacillus pumilus can serve as effective antimicrobial agents.
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