Bacterial growth curves are predictable from cellular Raman spectra*

Raman microscopy is an imaging technique that has been applied to cells to obtain Raman spectra that reflect the abundances of various biomolecules. It allows distinguishing cellular states in a label-free and non-destructive manner. Previously, employing spontaneous Raman scattering, we showed that cellular Raman spectra and transcriptomes could be linked in both S. pombe and E. coli, and that the transcriptomes could be reconstructed from Raman spectra (Kobayashi-Kirschvink et al., Cell Systems, 2018). Considering that omics information, which characterizes cellular states with molecular resolution, is linked to Raman spectra, we next asked whether Raman spectra could be linked to macroscopic quantities of cellular states. Our recent experimental and computational study indicates that different cellular states of single-gene knockout E. coli strains were distinguished by Raman spectra, and the entire population growth curves of different strains could be predicted by Raman spectra from cells in exponential phase. These results suggest that cellular Raman spectra have the potential to integrate macroscopic and microscopic characterizations of cellular states.