Imaging mass spectrometry reveals complex lipid distributions across Staphylococcus aureus biofilm layers

Imaging mass spectrometry reveals complex lipid distributions across Staphylococcus aureus biofilm layers

Rivera, Emilio S. (VanderBilt University)
Weiss, Andy (VanderBilt University)
Migas, L.G. (TU Delft Team Raf Van de Plas)
Freiberg, Jeffrey A. (VanderBilt University)
Djambazova, Katerina V. (VanderBilt University)
Neumann, Elizabeth K. (VanderBilt University)
Van de Plas, Raf (TU Delft Team Raf Van de Plas; VanderBilt University)
Spraggins, Jeffrey M. (VanderBilt University)
Skaar, Eric P. (VanderBilt University)
Caprioli, Richard M. (VanderBilt University)

2022

Introduction: Although Staphylococcus aureus is the leading cause of biofilm-related infections, the lipidomic distributions within these biofilms is poorly understood. Here, lipidomic mapping of S. aureus biofilm cross-sections was performed to investigate heterogeneity between horizontal biofilm layers. Methods: S. aureus biofilms were grown statically, embedded in a mixture of carboxymethylcellulose/gelatin, and prepared for downstream matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS). Trapped ion mobility spectrometry (TIMS) was also applied prior to mass analysis. Results: Implementation of TIMS led to a ∼ threefold increase in the number of lipid species detected. Washing biofilm samples with ammonium formate (150 mM) increased signal intensity for some bacterial lipids by as much as tenfold, with minimal disruption of the biofilm structure. MALDI TIMS IMS revealed that most lipids localize primarily to a single biofilm layer, and species from the same lipid class such as cardiolipins CL(57:0) – CL(66:0) display starkly different localizations, exhibiting between 1.5 and 6.3-fold intensity differences between layers (n = 3, p < 0.03). No horizontal layers were observed within biofilms grown anaerobically, and lipids were distributed homogenously. Conclusions: High spatial resolution analysis of S. aureus biofilm cross-sections by MALDI TIMS IMS revealed stark lipidomic heterogeneity between horizontal S. aureus biofilm layers demonstrating that each layer was molecularly distinct. Finally, this workflow uncovered an absence of layers in biofilms grown under anaerobic conditions, possibly indicating that oxygen contributes to the observed heterogeneity under aerobic conditions. Future applications of this workflow to study spatially localized molecular responses to antimicrobials could provide new therapeutic strategies.

Biofilms
Imaging Mass Spectrometry
Lipids
Trapped Ion Mobility

http://resolver.tudelft.nl/uuid:edfa5349-3acf-4b74-a0bc-8ab55cc279ff

https://doi.org/10.1016/j.jmsacl.2022.09.003

2667-145X

Journal of Mass Spectrometry and Advances in the Clinical Lab, 26, 36-46

Institutional Repository

journal article

© 2022 Emilio S. Rivera, Andy Weiss, L.G. Migas, Jeffrey A. Freiberg, Katerina V. Djambazova, Elizabeth K. Neumann, Raf Van de Plas, Jeffrey M. Spraggins, Eric P. Skaar, Richard M. Caprioli