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BioMed Research International
Volume 2013, Article ID 512495, 8 pages
Research Article

A Biosurfactant-Sophorolipid Acts in Synergy with Antibiotics to Enhance Their Efficiency

Biochemical Sciences Division, National Chemical Laboratory, Homi Bhabha Road, Pune Maharashtra 411008, India

Received 11 April 2013; Revised 22 July 2013; Accepted 2 August 2013

Academic Editor: Ramkrishna Sen

Copyright © 2013 Kasturi Joshi-Navare and Asmita Prabhune. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Sophorolipids (SLs), biosurfactants with antimicrobial properties, have been tried to address the problem of antibiotic resistance. The synergistic action of SL and antibiotics was checked using standard microdilution and spread plate methods. With Staphylococcus aureus, SL-tetracycline combination achieved total inhibition before 4 h of exposure while tetracycline alone couldnot achieve total inhibition till the end of 6 h. The inhibition caused by exposure of bacterium to SL-tetracycline mixture was ~25% more as compared to SL alone. In spite of known robustness of gram-negative bacteria, SL-cefaclor mixture proved to be efficient against Escherichia coli which showed ~48% more inhibition within 2 h of exposure as compared to cefaclor alone. Scanning electron microscopy of the cells treated with mixture revealed bacterial cell membrane damage and pore formation. Moreover, SLs being a type of asymmetric bola, they are expected to form self-assemblies with unique functionality. This led to the speculation that SLs being amphiphilic in nature can span through the structurally alike cell membrane and facilitate the entry of drug molecules.