Isolation of antimicrobial Tridecanoic acid from Bacillus sp. LBF-01 and its potentialization through silver nanoparticles synthesis: a combined experimental and theoretical studies

Tridecanoic acid (TDA), an antimicrobial compound, was isolated from Bacillus sp. LBF-01 and purified with the help of column and multidimensional liquid chromatography (MDLC), and characterized by Thin-layer chromatography (TLC), Electrospray Ionisation Mass Spectrometry (ESI-MS), Ultraviolet-Visible (UV-Vis), Fourier Transform Infrared Spectroscopy (FTIR), and Nuclear Magnetic Resonance (NMR) spectroscopic studies. Isolated TDA was potentialized through the synthesis of silver nanoparticles (AgNPs). UV-Vis, FTIR, and TEM analysis showed that synthesized AgNPs were stable, monodispersed, and spherical shape of average 19 nm diameter. Theoretical simulation using Density Functional Theory revealed that AgNPs were stabilized by the tridecanoate form of TDA with a binding energy of 59.9 kJ/mol. Both TDA and AgNPs showed strong antifungal and antibacterial activities against the plant and human pathogenic organisms, however, AgNPs showed higher antimicrobial efficacy than TDA. Synergistic activity of TDA and AgNPs with a fungicide (Bavistin) and antibiotics (Streptomycin and Ciprofloxacin) showed enhanced antimicrobial potency in the range of 20-32%. TDA and AgNPs cause severe morphological abnormalities in Fusarium oxysporum as observed under the light microscope. Hence, the study reveals that the antimicrobial TDA produced by Bacillus sp. LBF-01 have disease control potentiality, and also the TDA stabilized AgNPs have much higher antimicrobial efficacy against the target pathogens that could be utilized in plant and human diseases control. [GRAPHICS] .