Plant-endosymbiont mediated synthesis of silver nanobactericides with bioautography-guided partial purification of novel 1,2-benzenedicarboxylic acid, decyl octyl ester

In the present study, synthesis of silver nanobactericides was achieved from Curcuma longa L. and its endosymbiont for their antimicrobial activity. The nanobactericides exhibited notable antimicrobial potential against Escherichia coli and Staphylococcus aureus, as determined through broth dilution and minimum inhibitory concentration which ranged between 2.5 and 5 mg/mL. Characterization of nanobactericides revealed polydispersity with average size of 80 nm and crystalline nature showed distinct peaks. The Fourier transform infrared (FTIR) analysis revealed presence of exhibited peaks at 3362.24 cm⁻¹ (hydroxyl group), 1637.96 cm⁻¹ (carbonyl group), 1377.25 cm⁻¹ (alkane group), and 635.25 cm⁻¹ (alkyl group) which participated in the synthesis of nanobactericides. Endosymbiont crude extracts subjected to partial purification through thin-layer chromatography, and bioautography-guided fractionation identified an active compound at R_f 0.7 which showed clear zone of inhibition. The minimum inhibitory concentration of metabolite fraction was found to be 0.625 mg/mL against both the test pathogens. The dye degradation potential of nanobactericides was successful 81.27 % of degradation was achieved with safranin treated with silver nanobactericides from endosymbiont. Subsequently, nanobactericides synthesized from plants showed 59.88 % highest degradation with methylene blue. The profiling of metabolite was carried out with gas chromatography-mass spectrometry to identify as a novel metabolite, 1,2-benzenedicarboxylic acid, decyl octyl ester, showing antimicrobial potential against tested pathogens. The identified metabolite molecular formula was found to be C₂₆H₄₂O₄ with molecular weight of 418. These promising results, especially for the scarcely reported compound, contribute to the understanding of plant-endosymbiont-synthesized nanobactericides with significant antimicrobial properties. The molecular analysis revealed the endosymbiont's affinity to Pseudomonas aeruginosa, and its sequence has been deposited in GenBank (Accession number OR984817). The study concludes with importance of nanobactericides from plant-endosymbiont consortium, highlighting their antimicrobial efficacy against human and phytopathogens.