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. 2023 Nov 24;95(48):17733–17740. doi: 10.1021/acs.analchem.3c03595

Figure 4.

Figure 4

O-PTIR imaging unveils PHB-producing cells within a B. sphaericus B0769 population. (a) Single-frequency image showing the distribution of amide I vibration from proteins (1656 cm–1). (b) False-color map obtained by the ratio 1727/1656 cm–1 showing the relative intracellular PHB content. (c) FTIR spectrum from commercial PHB (green, top) as well as O-PTIR signatures acquired on single-point mode from 18 bacterial cells including eight PHB-negative cells and 10 PHB-positive cells. (d) Details on shifts in the ester carbonyl band stretching vibrations due to variations in PHB crystallinity. (e) Average and standard deviation calculated by the 1727/1656 cm–1 area ratio from O-PTIR signatures on single-point mode from cells identified in (b) as being PHB producers (n = 10) or nonproducers (n = 8). (f,g) PCA scores and loadings plots, respectively, obtained from O-PTIR spectra acquired from 18 bacterial cells; values in parentheses are the percentage total explained variance (TEV). Plots in (c,d,g) are offset for clarity. Scale bar in (a,b) is 8 μm.