Biofilm hydrophobicity in environmental isolates of Bacillus subtilis

Margarita Kalamara, James Abbott, Cait E. MacPhee, Nicola Stanley-Wall (Lead / Corresponding author)

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)
132 Downloads (Pure)


Biofilms are communities of bacteria that are attached to a surface and surrounded by an extracellular matrix. The extracellular matrix protects the community from stressors in the environment, making biofilms robust. The Gram-positive soil bacterium Bacillus subtilis, particularly the isolate NCIB 3610, is widely used as a model for studying biofilm formation. B. subtilis NCIB 3610 forms colony biofilms that are architecturally complex and highly hydrophobic. The hydrophobicity is linked, in part, to the localisation of the protein BslA at the surface of the biofilm, which provides the community with increased resistance to biocides. As most of our knowledge about B. subtilis biofilm formation comes from one isolate, it is unclear if biofilm hydrophobicity is a widely distributed feature of the species. To address this knowledge gap, we collated a library of B. subtilis soil isolates and acquired their whole genome sequences. We used our novel isolates to examine biofilm hydrophobicity and found that, although BslA is encoded and produced by all isolates in our collection, hydrophobicity is not a universal feature of B. subtilis colony biofilms. To test whether the matrix exopolymer poly γ-glutamic acid could be masking hydrophobicity in our hydrophilic isolates, we constructed deletion mutants and found, contrary to our hypothesis, that the presence of poly γ-glutamic acid was not the reason for the observed hydrophilicity. This study highlights the natural variation in the properties of biofilms formed by different isolates and the importance of using a more diverse range of isolates as representatives of a species.

Original languageEnglish
Number of pages16
Issue number9
Early online date6 Sept 2021
Publication statusPublished - 2021


  • Bacillus subtilis
  • BslA
  • biofilm
  • hydrophobicity
  • soil isolates

ASJC Scopus subject areas

  • Microbiology


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