Surfactin Shows Relatively Low Antimicrobial Activity against Bacillus subtilis and Other Bacterial Model Organisms in the Absence of Synergistic Metabolites

Lars Lilge, Nadine Ersig, Philipp Hubel, Moritz Aschern, Evelina Pillai, Peter Klausmann, Jens Pfannstiel, Marius Henkel, Kambiz Morabbi Heravi, Rudolf Hausmann

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Surfactin is described as a powerful biosurfactant and is natively produced by Bacillus subtilis in notable quantities. Among other industrially relevant characteristics, antimicrobial properties have been attributed to surfactin-producing Bacillus isolates. To investigate this property, stress approaches were carried out with biotechnologically established strains of Corynebacterium glutamicum, Bacillus subtilis, Escherichia coli and Pseudomonas putida with the highest possible amounts of surfactin. Contrary to the popular opinion, the highest growth-reducing effects were detectable in B. subtilis and E. coli after surfactin treatment of 100 g/L with 35 and 33%, respectively, while P. putida showed no growth-specific response. In contrast, other antimicrobial biosurfactants, like rhamnolipids and sophorolipids, showed significantly stronger effects on bacterial growth. Since the addition of high amounts of surfactin in defined mineral salt medium reduced the cell growth of B. subtilis by about 40%, the initial stress response at the protein level was analyzed by mass spectrometry, showing induction of stress proteins under control of alternative sigma factors σB and σW as well as the activation of LiaRS two-component system. Overall, although surfactin is associated with antimicrobial properties, relatively low growth-reducing effects could be demonstrated after the surfactin addition, challenging the general claim of the antimicrobial properties of surfactin.

Original languageEnglish
Article number779
JournalMicroorganisms
Volume10
Issue number4
DOIs
StatePublished - Apr 2022
Externally publishedYes

Keywords

  • Bacillus subtilis
  • biosurfactants
  • secondary metabolites
  • stress response
  • surfactin

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