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Antibiotic resistance against present antibiotics is rising at an alarming rate with need for discovery of advanced methods to treat infections caused by resistant pathogens. Silver nanoparticles are known to exhibit satisfactory antibacterial and antibiofilm activity against different pathogens. In the present study, the AgNPs were synthesized chemically and characterized by UV-Visible spectroscopy, scanning electron microscopy, and X-ray diffraction. Antibacterial activity against MDR K. pneumoniae strains was evaluated by agar diffusion and broth microdilution assay. Cellular protein leakage was determined by the Bradford assay. The effect of AgNPs on production on extracellular polymeric substances was evaluated. Biofilm formation was assessed by tube method qualitatively and quantitatively by the microtiter plate assay. The cytotoxic potential of AgNPs on HeLa cell lines was also determined. AgNPs exhibited an MIC of 62.5 and 125 μg/ml, while their MBC is 250 and 500 μg/ml. The production of extracellular polymeric substance decreased after AgNP treatment while cellular protein leakage increased due to higher rates of cellular membrane disruption by AgNPs. The percentage biofilm inhibition was evaluated to be 64% for K. pneumoniae strain MF953600 and 86% for MF953599 at AgNP concentration of 100 μg/ml. AgNPs were evaluated to be minimally cytotoxic and safe at concentrations of 15-120 μg/ml. The data evaluated by this study provided evidence of AgNPs being safe antibacterial and antibiofilm compounds against MDR K. pneumoniae.

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Floating treatment wetland (FTW) is an effective and sustainable technology for wastewater treatment. It has been widely adopted for treating various kinds of polluted water including agricultural runoff, stormwater, industrial effluents, etc. In FTWs, plants are vegetated on a floating mat while their roots are extended down to the contaminated water hence acting as biological filters. Nutrients and potentially toxic metal(s)/element(s) are taken up from the wastewater by plants through their roots whereas organic matter is degraded by the microorganisms forming biofilms on the roots and mat surface. Additionally, organic contaminants which are already taken up by the plants are degraded by endophytic bacteria in planta. This article provides an overview of FTWs and their application for wastewater treatment. The key factors which have an impact on the performance of FTWs are also described. Lastly, the potential role of combined use of plants and bacteria in FTWs for the maximum remediation of polluted water is emphasized.