Genomic and transcriptomic insights into how bacteria withstand high concentrations of benzalkonium chloride biocides

Minjae Kim, Janet K. Hatt, Michael R. Weigand, Raj Krishnan, Spyros G. Pavlostathis, Konstantinos T. Konstantinidis

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


Benzalkonium chlorides (BAC) are commonly used biocides in broadspectrum disinfectant solutions. How microorganisms cope with BAC exposure remains poorly understood, despite its importance for disinfection and disinfectantinduced antibiotic resistance. To provide insights into these issues, we exposed two isolates of an opportunistic pathogen, Pseudomonas aeruginosa, to increasing concentrations of BAC. One isolate was preadapted to BAC, as it originated from a bioreactor fed with subinhibitory concentrations of BAC for 3 years, while the other originated from a bioreactor that received no BAC. Replicated populations of both isolates were able to survive high concentrations of BAC, up to 1,200 and 1,600 mg/ liter for the non- and preadapted strains, respectively, exceeding typical application doses. Transcriptome sequencing (RNA-seq) analysis revealed upregulation of efflux pump genes and decreased expression of porins related to BAC transport as well as reduced growth rate. Increased expression of spermidine (a polycation) synthase genes and mutations in the pmrB (polymyxin resistance) gene, which cause a reduction in membrane negative charge, suggested that a major adaptation to exposure to the cationic surfactant BAC was to actively stabilize cell surface charge. Collectively, these results revealed that P. aeruginosa adapts to BAC exposure by a combination of mechanisms and provided genetic markers to monitor BAC-resistant organisms that may have applications in the practice of disinfection.

Original languageEnglish
Article numbere00197-18
JournalApplied and Environmental Microbiology
Issue number12
StatePublished - Jun 1 2018

Bibliographical note

Funding Information:
This work was supported by U.S. National Science Foundation awards 0967130 to S.G.P. and K.T.K. and 1241046 to K.T.K. We have no conflicts of interest to declare.

Publisher Copyright:
© 2018 American Society for Microbiology.


  • Adaptation
  • Disinfectants
  • Genomics
  • Pseudomonas aeruginosa
  • Transcriptomics

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology


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