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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Microbiol. | doi: 10.3389/fmicb.2019.02664

MexAB-OprM efflux pump of Pseudomonas aeruginosa offers tolerance to carvacrol: A herbal antimicrobial agent

  • 1Division of Bacteriology & Mycology, Indian Veterinary Research Institute, India
  • 2Division of Epidemiology, Indian Veterinary Research Institute, India
  • 3Division of Veterinary Public Health, Indian Veterinary Research Institute, India
  • 4Division of Veterinary Biotechnology, Indian Veterinary Research Institute (IVRI), India

Carvacrol has been proven to be a potent herbal antimicrobial agent against many pathogens. However, some multi drug resistant strains of Pseudomonas aeruginosa are tolerant to many herbal compounds including carvacrol. The tolerance of Pseudomonas aeruginosa to carvacrol is not well studied. This study aims to identify the gene(s) associated with carvacrol tolerance thus to understand its mechanisms in P. aeruginosa. Herbal drug resistant MDR strain of P. aeruginosa was isolated from the field samples. Carvacrol sensitive mutant was generated using transposon mutagenesis. The inactivated gene in the mutant was identified as mexA, which is a part of mexA-mexB-oprM efflux pump. Inactivation of mexA gene resulted in 32.5 fold reduction in MIC of carvacrol whereas 80 folds reduction was observed in the presence of PAβN. The organism was completely killed within 3 h of incubation in all combinations of carvacrol and PAβN. Interestingly, mexA inactivation did not affect the tolerance of other herbal compounds used. This study reveals that the tolerance of carvacrol in P. aeruginosa is mediated by the MexA-MexB-OprM efflux pump but not to other herbal antimicrobial compounds used in this study

Keywords: mexA, Pseudomonas, efflux, Carvacrol (C), MIC

Received: 22 Mar 2019; Accepted: 01 Nov 2019.

Copyright: © 2019 Pesingi, Singh, Pesingi, Bhardwaj, Singh, KUMAWAT, Sinha and Gandham. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Dr. Prasanna V. Pesingi, Division of Bacteriology & Mycology, Indian Veterinary Research Institute, Bariely, India, prasanna.thamizhanbu.vadhana@gmail.com
Dr. Bhoj R. Singh, Division of Epidemiology, Indian Veterinary Research Institute, Bareilly, India, brs1762@gmail.com