Impact of Moringa oleifera leaf extract on Biofilm formation and Swarming motility of Pseudomonas aeruginosa HRW.1-S3

Saxena, Manini (2025) Impact of Moringa oleifera leaf extract on Biofilm formation and Swarming motility of Pseudomonas aeruginosa HRW.1-S3. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS Dissertation of Manini Saxena (20MS190)) 20MS190_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (3MB)

Abstract

Pseudomonas aeruginosa is a superbug known to have enhanced anti-microbial resistance, and hence is a major threat in healthcare. The uncontrolled use of antibiotics has engendered these pathogens to develop anti-microbial resistance by using multicellularity as their defence mechanism. This study explores an alternative approach by studying the effect of Moringa oleifera leaf extract on the biofilm formation and swarming ability of this bacteria. The leaf extract was prepared via ethanolic extraction, and its antimicrobial efficacy was assessed against Pseudomonas aeruginosa environmental isolate HRW.1-S3 through minimum inhibitory concentration, biofilm load, LIVE/DEAD staining, colony forming unit assay, swarming motility assay, and extracellular polymeric substance estimation. Morphological alterations were examined via microscopic techniques, like scanning electron microscopy and atomic force microscopy. MIC assay showed a dose-dependent reduction in planktonic bacterial growth, however, biofilm assay indicated increased biofilm formation in presence of increasing Moringa oleifera treatment with enhanced extracellular polymeric substance production. LIVE/DEAD staining confirmed reduced viable cells within the matrix. Swarming motility and flagellation were enhanced, as seen through microscopic studies. All extracellular polymeric components except eDNA showed an increase in swarming conditions. In conclusion, Moringa oleifera leaf extract shows antimicrobial activity but increases biofilm though with less viable cells. M. oleifera also has a positive impact on bacterial swarming suggesting a complex bacterial defensive strategy at work.

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