Antibacterial Evaluation of Curcuma longa (Turmeric) and Hibiscus Rosa-sinensis Extracts Against Waterborne Pathogens from Contaminated Tap Water

Background: Rising antimicrobial resistance has renewed interest in plant-derived and plantassistedantibacterial agents, and contaminated drinking water continues to be a major sourceof bacterial illness.Objective: To isolate Staphylococcus aureus and Escherichia coli from tainted municipal tapwater in Meerut, Uttar Pradesh, and evaluate the antimicrobial efficacy of flower extracts fromHibiscus rosa-sinensis and Curcuma longa rhizome using silver nanoparticles (AgNPs) madefrom each.Methods: 200 water samples from 50 municipal taps were cultured on MacConkey andmannitol salt agar. Isolates were identified by colony morphology, gram staining, andbiochemical tests. AgNPs were prepared by reacting the extracts with 1 mM of silver nitrateand checked for color changes and examined with UV-Visible spectroscopy. Zones ofinhibition (ZOIs) were determined by the agar well diffusion method and evaluated with theKruskal-Wallis test.Results: Eighty-eight isolates were collected: 48 E. Coli (24% of samples) and 40 S. Aureus(20%). Both AgNPs had a surface plasmon resonance peak to 420 nm. Hibiscus AgNPscreated the zones (15.43 ± 1.93 mm for E. Coli; 16.50 ± 0.97 mm, for S. Aureus) then CurcumaAgNPs (13.89 ± 1.66 mm; 14.40 ± 1.08 mm). Crude extracts made zones (9.07 to 11.10 mm)and 1 mM silver nitrate made about 11.9 mm. The differences were significant (p < 0.05).Conclusion: AgNPs showed 48 to 64 percent inhibition compared to their crude extracts.Among them the Hibiscus AgNPs were the most effective. This conclusion is still preliminary.The characterisation was only done using UV- spectroscopy. There was no dose–responseanalysis carried out on the isolates that were presumed to be active. More work is neededbefore these AgNPs can be used in water treatment.