The Synergistic Effects of Rhamnolipids and Antibiotics Against Bacteria


  • Ella Shusterman Ms. Meredith McCarthy
  • Abigail Mottahedeh
  • Merideth McCarthy



antibiotics, rhamnolipids, biosurfactant, cell membrane permeability


Antibiotics are used to combat bacterial infections by slowing down and preventing the proliferation of bacteria. Antibiotic resistance is a threat to human health, attributed to its overuse and misuse. Altering the membrane permeability to induce antibiotic uptake may be an effective strategy used against both Gram-positive and Gram-negative infectious bacteria. Rhamnolipids (RLs) are biosurfactants produced by Pseudomonas aeruginosa. RLs surface-active properties operate by creating holes in bacterial cell membranes, increasing target cell permeability; allowing antibiotics to penetrate the cell. 


Rhamnolipids enhance the effect of antibiotics by targeting the intracellular machinery of bacteria. This project tested the susceptibility of bacteria when exposed to antibiotics with and without the addition of RLs, to quantitatively determine if RLs increase antibiotic potency. By analyzing the zones of inhibition data, the results demonstrated that RLs potentiated the antibiotics. Notably, kanamycin coupled with RLs had the most effect inhibiting bacterial growth. 

To further assess rhamnolipid biosynthesis, a BLAST search was performed exclusively on two genes, rhlA and rhlB. These genes code for the production of two proteins necessary for rhamnolipids. The search indicated a 48% correlation with putative proteins found in Burkholderia pseudomallei. Therefore, based on the experimental results and the BLAST analysis, further research should be conducted to explore the possible role of using rhamnolipids as antibiotic enhancers. Specifically, future experiments could focus on isolating the putative proteins of B.pseudomallei to genetically modify E.coli. Furthermore, isolated studies analyzing the genes of proteins to determine their role in the pathogenicity of Burkholderia species.


Download data is not yet available.

References or Bibliography

Allison, K.R., Brynildsen, M.P. & Collins, J.J. (2011). Metabolite-Enabled Eradication of Bacterial Persisters by Aminoglycosides. Nature, 473: 216–220.

Aslam, B., Wang, W., Arshad, M.I., Khurshid, M., Muzammil, S., Rasool, M.H., Nisar, M.A., Alvi, R.F., Aslam, M.A., Qamar, M.U., Salamat, M.K. & Baloch, Z. (2018). Antibiotic Resistance: a Rundown of a Global Crisis. Infection and Drug Resistance, 11: 1645-1658.

Delcour, A.H. (2009). Outer Membrane Permeability and Antibiotic Resistance. Biochimica Et Biophysica Acta, 1794(5): 808-816.

Dusane, D.H., Zinjarde, S.S., Venugopalan, V.P., McLean, R.J., Weber, M.M. & Rahman, P.K. (2010). Quorum Sensing: Implications on Rhamnolipid Biosurfactant Production. Biotechnology and Genetic Engineering Reviews, 27: 159-84.

Fu, T.K., Ng, S.K., Chen, Y.E., Lee, Y.C., Demeter, F., Herczeg, M., Borbas, A., Chiu, C.H., Lan, C.Y., Chen, C.L. & Chang, M.D. (2019). Rhamnose Binding Protein as an Anti-Bacterial Agent-Targeting Biofilm of Pseudomonas Aeruginosa. Marine Drugs, 17(6): 355.

Kiss, K., Ng, W.T. & Li, Q. (2017) Production of Rhamnolipids-Producing Enzymes of Pseudomonas in E.coli and Structural Characterization. Frontiers of Chemical Science and Engineering, 11: 133-138.

Krause, K.M., Serio, A.W., Kane, T.R. & Connolly, L.E. (2016) Aminoglycosides: An Overview. Cold Spring Harbor Perspectives in Medicine, 6(6): a027029.

Leekha, S., Terrell, C.L. & Edson, R.S. (2011). General Principles of Antimicrobial Therapy. Mayo Clinic Proceedings, 86(2), 156-167.

Nathan, C. & Cars, O. (2014) Antibiotic Resistance - Problems, Progress, and Prospects: NEJM. The New England Journal of Medicine, 371: 1761-1763.

Pearson, J.P., Pesci, E.C. & Iglewski, B.H. (1997). Roles of Pseudomonas Aeruginosa las and rhl Quorum-Sensing Systems in Control of Elastase and Rhamnolipid Biosynthesis Genes. Journal of Bacteriology, 179(18): 5756-5767.

Pearson, W.R. (2013) An Introduction to Sequence Similarity (“Homology”) Searching. Current Protocols in Bioinformatics, 03:10.1002/0471250953.

Qingxin, Li (2017). Rhamnolipid Synthesis and Production with Diverse Resources. Frontiers of Chemical Science and Engineering, 11(1): 27-36.

Radlinski, L.C, Rowe, S.E., Brzozowski, R., Wilkinson, A.D., Huang, R., Eswara, P. & Conlon, B.P. (2019) Chemical Induction of Aminoglycoside Uptake Overcomes Antibiotic Tolerance and Resistance in Staphylococcus aureus. Cell Chemical Biology, 26(10): 1355-1364.

Randhawa, K.K. & Rahman, P.K. (2014) Rhamnolipid Biosurfactants-Past, Present, and Future Scenario of Global Market. Frontiers in Microbiology, 5: 454.

Wood, T.L., Gong, T., Zhu, L., Miller, J. Miller, D.S., Yin, B. & Wood, T.K. (2018). Rhamnolipids from Pseudomonas Aeruginosa Disperse the Biofilms of Sulfate-Reducing Bacteria. NPJ: Biofilms and Microbiomes, 4:22.

Yazdani, M., Naderi-Manesh, H., Khajeh, K., Soudi, M.R., Asghari, S.M. & Sharifzadeh, M. (2009). Isolation and Characterization of a Novel Gamma-Radiation-Resistant Bacterium from Hot Spring in Iran. Journal of Basic Microbiology, 49(1): 119-27.

Zulianello, L., Canard, C., Kohler, T., Caille, D., Lacroix, J.S. & Meda, P. (2006). Rhamnolipids Are Virulence Factors That Promote Early Infiltration of Primary Human Airway Epithelia by Pseudomonas Aeruginosa. American Society for Microbiology: Infection and Immunity, 74(6): 3134-3147.



How to Cite

Shusterman, E., Mottahedeh, A., & McCarthy, M. (2021). The Synergistic Effects of Rhamnolipids and Antibiotics Against Bacteria. Journal of Student Research, 10(2).



HS Research Articles