Table 2.
Overview of Raman active modes found in cable bacteria.
| Peak | CB | FS | Intensity | Annotation | Ref. |
|---|---|---|---|---|---|
| 53 cm−1 | ? | Low | Ni-cofactor: annotation uncertain | [1] | |
| 95 cm−1 | ? | Low | Ni-cofactor: annotation uncertain | [1] | |
| 121 cm−1 | ? | Low | Ni-cofactor: annotation uncertain | [1] | |
| 182 cm−1 | Low | Ni-cofactor: δ(SNiS) − S-Ni-S deformation | [2] | ||
| 278 cm−1 | Low | Ni-cofactor: ν(Ni-S)asym − Ni-S stretching | [2] | ||
| 308 cm−1 | Low | Ni-cofactor: annotation uncertain | [1] | ||
| 367 cm−1 | High | Ni-cofactor: ν(Ni-S)sym − Ni-S stretching | [2, 3] | ||
| 448 cm−1 | Low | Ni-cofactor: annotation uncertain | [1] | ||
| 496 cm−1 | High | Ni-cofactor: ν(C-S) + ring deformation | [2, 3] | ||
| 622 cm−1 | Low | Ni-cofactor: annotation uncertain | [1] | ||
| 680 cm−1 | Medium | Cytochromes: ν(Ca-S) | [4, 5] | ||
| 750 cm−1 | Medium | Cytochromes: ν15 − Pyrrole breathing | [4, 5] | ||
| 856 cm−1 | Low | Tyrosine: Fermi resonance − ν1 + 2ν16a | [6] | ||
| 976 cm−1 | High | Phosphate: ν(PO43−) − Symmetric phosphate stretching | [7, 8] | ||
| 1,004 cm−1 | Medium | Phenyl alanine: Ring breathing | [9] | ||
| 1,130 cm−1 | Medium | Cytochromes: ν22 − vibrations of side radicals Cb-CH3 | [4, 5] | ||
| 1,146 cm−1 | High | Ni-cofactor: ν(C=S) − thiocarbonyl radical stretching | [10] | ||
| 1,181 cm−1 | High | Ni-cofactor: ν(C=S) − thiocarbonyl radical stretching | [10] | ||
| 1,219 cm−1 | High | Ni-cofactor: ν(C=S) − thiocarbonyl radical stretching | [10] | ||
| 1,360 cm−1 | High | Cytochromes: ν4 − symmetric pyrrole half-ring stretching | [4, 5] | ||
| 1,450 cm−1 | Medium | Carbohydrates, lipids, protein: ρ(CH2) − CH2 scissoring | [11–14] | ||
| 1,588 cm−1 | Medium | Cytochromes: ν19 − ν(CαCm)asym | [4, 5] | ||
| 1,640 cm−1 | Medium | Cytochromes: ν10 − ν(CαCm)asym | [4, 5] | ||
| 1,660 cm−1 | Medium | Proteins: ν(C=O) − Carbonyl stretching (Amide I) | [15] | ||
| 2,940 cm−1 | High | Carbohydrates, DNA, lipids, proteins: ν(C-H) − C-H stretching | [10, 13, 16, 17] |
Dark gray shaded areas indicate modes observed in native cable bacterium filaments (CB) and fiber skeletons (FS). Light gray shaded areas indicate modes attributed to the Ni-cofactor. [1] this work, [2] Johnson (2004), [3] Boschker et al. (2021), [4] Virdis et al. (2014), [5] Milazzo et al. (2018), [6] Siamwiza et al. (1975), [7] Frost et al. (2016), [8] Nkebiwe et al. (2022), [9] Freire et al. (2017), [10] Petrenko et al. (2006), [11] Czamara et al. (2015), [12] Ferraro et al. (2003), [13] Salmaso et al. (1994), [14] Wiercigroch et al. (2017), [15] Miura and Thomas (1995), [16] Kengne-Momo et al. (2012), [17] Prescott et al. (1984). ? indicates vibrational modes which were not examined.