Characterization of Biofilms Produced by Bacillus Wild Isolates

Abstract

Many bacteria form complex multicellular communities known as biofilms. Biofilms are a common source of human infections and are associated with chronic infections and with infections resulting from biomedical implants. Bacillus subtilis has been used as a model organism to study biofilms, leading to important insights into how biofilms are regulated and form. However, most research has examined biofilm formation in a single laboratory strain of B. subtilis. We sought to examine differences in biofilm formation between twenty wild isolates that had been published by others to belong to the species B. subtilis. We characterized the biofilm phenotypes of the strains on several types of media and also sequenced the whole genome of each of the strains. We found a wide array of biofilm phenotypes with most being more intense than biofilms of the laboratory strain. Furthermore, biofilm phenotypes and intensity of the biofilm were media‐dependent. Our genetic results indicated that nine of the twenty strains are not actually Bacillus subtilis, but are likely to be a related species, Bacillus velezencis. Interestingly, biofilm strength did not correlate with species. Among the B. subtilis strains, several coding genetic variations were identified in genes important for biofilm formation. Together our study provides insight into variation in biofilm formation among related bacteria and creates a list of possible variations that can be tested for their impact on biofilm formation.Support or Funding InformationResearch was supported by the National Institute Of General Medical Sciences of the National Institutes of Health under Award Number R15GM135861. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.