2.1. Bacterial strains and reagents

The medicinal plant, Tinospora cordifolia was selected from Gir forest region of Gujarat, India on the basis of its medicinal property [¹¹]. Silver nitrate, AR grade was procured from Thermo Fisher Scientific, Vadodara, India. The two bacterial strains one Gram positive (Bacillus megaterium MTCC 7192) and one Gram negative (Pseudomonas aeruginosa MTCC 741) are clinical isolates that were obtained from the microbial type culture collection (MTCC), Institute of microbial technology, Chandigarh, India. Bacterial strains were cultivated on Nutrient broth medium (pH 7.3 ± 0.1; HiMedia, Vadodara, India) at 37 °C with shaking at 150 rpm. Bacterial cell suspensions were diluted with a sterile Milli-Q water (pH 7) to obtain a final concentration of 10⁸ CFU/ml. Four broad spectrum antibiotics, namely, amoxicillin (Sun pharmaceutical, Ankleshwar, India), chloramphenicol (Alps pharmaceuticals, Uttarakhand, India), trimethoprim-sulfamethoxazole (Abbott Healthcare, Mumbai, Maharashtra), and linezolid (Glenmark pharmaceutical, Ankleshwar, India) were used for bactericidal assay. All other chemicals used in this study were analytical grade (Sigma Aldrich, Ahmedabad, India).