Antibacterial activities of novel antimicrobial metabolites by <i>Klebsiella pneumoniae</i> strain EKA-02 from dump site soil and surface water

The increasing prevalence of antibiotic-resistant bacteria has necessitated the search for novel antimicrobial agents from microbial sources. This study investigated the antibacterial potential of Klebsiella pneumoniae isolates, characterized through morphological, biochemical, and molecular approaches. The isolates were confirmed via 16S rDNA sequencing, aligning with established phylogenetic analyses and supporting their taxonomic classification. The antibacterial activity of the identified K. pneumoniae strain EKA-02 against Bacillus subtilis and Enterococcus sp. was assessed, revealing significant inhibition zones, with diameters reaching up to 38 mm. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were determined, with an MIC of 3.125 mg/ml and an MBC of 6.25 mg/ml, demonstrating the bactericidal efficacy of the microbial extract. Thin-layer chromatography (TLC) profiling indicated the presence of multiple bioactive compounds, and gas chromatography-mass spectrometry (GC-MS) analysis identified octadecane, heptadecane, tetradecanoic acid, and 7β-acetoxyvouacapane as predominant antimicrobial constituents. The findings highlight the potential of K. pneumoniae EKA-02 as a source of novel antimicrobial agents, particularly against Gram-positive bacteria. The presence of fatty acids, terpenes, and halogenated compounds suggests a multifaceted mode of action. The study reinforces the rich dynamics of untapped microbial resources in the Nigerian environment which could be focused in order to address the global antibiotic resistance crisis.