Fig. 1
From: Ultra-sensitive isotope probing to quantify activity and substrate assimilation in microbiomes
Modeled spectra of three E. coli peptides after 1/8 generations of growth on 1% (left) and 10% (right) 13C1-6 glucose (13C/12C 0.02 and 0.11 respectively). Assimilation of 13C into peptides leads to a shift of matter away from the monoisotopic mass (shown as *). The resulting peak intensity changes are shown in red—for peaks with decreased intensity -, and blue - for peaks with increased intensity after labeling. Dashed lines show experimentally determined average detection limits for peaks (see “Methods” section). Peaks below the dashed line would not be recorded by the mass spectrometer. Percentages above lines indicate how much of the actual change is detectable in practice. Peptide 1 - IGLETAR; peptide 2 - AFEMGWRPDMSGVK; peptide 3 - QIQEALQYANQAQVTKPQIQQTGEDITQDTLFLLGSEALESMIK