Label-free molecular imaging of bacterial communities of the opportunistic pathogen Pseudomonas aeruginosa

Nameera Baig, Sneha Polisetti, Nydia Morales-Soto, Sage J.B. Dunham, Jonathan V. Sweedler, Joshua D. Shrout, Paul W. Bohn

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Biofilms, such as those formed by the opportunistic human pathogen Pseudomonas aeruginosa are complex, matrix enclosed, and surface-associated communities of cells. Bacteria that are part of a biofilm community are much more resistant to antibiotics and the host immune response than their free-floating counterparts. P. aeruginosa biofilms are associated with persistent and chronic infections in diseases such as cystic fibrosis and HIV-AIDS. P. aeruginosa synthesizes and secretes signaling molecules such as the Pseudomonas quinolone signal (PQS) which are implicated in quorum sensing (QS), where bacteria regulate gene expression based on population density. Processes such as biofilms formation and virulence are regulated by QS. This manuscript describes the powerful molecular imaging capabilities of confocal Raman microscopy (CRM) and surface enhanced Raman spectroscopy (SERS) in conjunction with multivariate statistical tools such as principal component analysis (PCA) for studying the spatiotemporal distribution of signaling molecules, secondary metabolites and virulence factors in biofilm communities of P. aeruginosa. Our observations reveal that the laboratory strain PAO1C synthesizes and secretes 2-alkyl-4-hydroxyquinoline N-oxides and 2-alkyl-4-hydroxyquinolones in high abundance, while the isogenic acyl homoserine lactone QS-deficient mutant (δlasIδrhlI) strain produces predominantly 2-alkyl-quinolones during biofilm formation. This study underscores the use of CRM, along with traditional biological tools such as genetics, for studying the behavior of microbial communities at the molecular level.

Original languageEnglish (US)
Title of host publicationBiosensing and Nanomedicine IX
EditorsHooman Mohseni, Massoud H. Agahi, Manijeh Razeghi
ISBN (Electronic)9781510602519
StatePublished - 2016
EventBiosensing and Nanomedicine IX - San Diego, United States
Duration: Aug 28 2016Aug 31 2016

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


OtherBiosensing and Nanomedicine IX
Country/TerritoryUnited States
CitySan Diego


  • Biofilms
  • Phenazines
  • Pseudomonas aeruginosa
  • Quinolones
  • Raman spectroscopy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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