Table 1.
Comparison of isotopic composition measurement by NanoSIMS and by IRMS (mean value with standard error).
| Isotopic composition of the culture media | Isotopic abundance in raw E. coli cell pellets analysed by IRMS (duplicated analysis) | NanoSIMS analysis on a set of single cells (10 replicate analysis) | |||
|---|---|---|---|---|---|
| 13C | 15N | 13C atom % | 15N atom % | 13C abundance 13C/(12C+13C) | 15N abundance 15N/(14N+15N) |
| Natural | Natural | 1.10 ± 0.00% | 0.39 ± 0.00% | 1.1 ± 0.03%a | 0.40 ± 0.01% |
| 10% | Natural | 8.85 ± 0.09% | 0.37% ± 0.00% | 9.6 ± 0.17%a | – |
| 40% | Natural | 33.99 ± 0.08% | 0.37% ± 0.00% | 32.6 ± 0.22%b | – |
| 70% | Natural | 58.12 ± 0.47% | 0.38% ± 0.00% | 58.0 ± 0.41%a | – |
| 99% | Natural | – | – | 86.8 ± 0.63%a | – |
| Natural | 10% | 1.10 ± 0.00% | 9.25 ± 0.10% | – | 10.1 ± 0.17% |
| Natural | 40% | 1.10 ± 0.00% | 36.46 ± 0.21% | – | 38.9 ± 0.19%b |
| Natural | 70% | 1.10 ± 0.00% | 63.39% | – | 66.5 ± 0.13% |
| Natural | 99% | – | – | – | 94.2 ± 0.16% |
| 50% | 50% | 49.10 ± 0.01% | 44.21 ± 0.25% | 42.1 ± 0.35%b | 39.8 ± 0.16%b |
a
Analysis performed on fixed cells.
b
Analysis performed on fixed and pre-hybridized cells. Other values were obtained on unfixed and non-hybridized cells.
13C and 15N isotopic composition of the different pure E. coli cell cultures were determined by IRMS. NanoSIMS analysis data were obtained by image analysis procedure.