µ-Raman and GC-MS to interrogate the heterogeneity of deuterium-label incorporation on the single cell vs. fatty acid isotopologue level.

O. The deuteration levels of single cells and fatty acids supported one another quantitatively. Besides demonstrating good agreement between both datasets, they were also shown to synergistically complement each other. Information on different cell generations was derived from clusters of varying degrees of cell deuteration, and heterogeneities between different fatty acids and their isotopologues were revealed. Additionally, variations in carbon and deuterium sources influenced fatty acid profiles and biomass deuterations. This proof-of-principle study underscores the consistent and complementary nature of lipid-SIP and single-cell-SIP approaches, providing a benchmark for future research on microbial community dynamics and organic substrate biodegradation.