Table 6.

Main absorption peaks and vibrational assignment with functional groups interpretation of L. plantarum strain TA4 exposed with Zn²⁺

Absorption peak (cm−1)	Vibrational assignment	Functional group	References
3273.16	O–H stretching and N–H asymmetric stretching	Amine and hydroxyl	[75]
1614.88	C=O stretching	Amide I	[45]
1550.42	N–H bending	Amide II	[45]
1423.64	CH2/CH3 bending	Lipids and proteins peptide	[76]
1367.59	C=O of COO− symmetric stretching	Carboxylate	[19]
1221.1	P=O. P–O	Phosphate	[45]
1095.79	C–C=O, C–O–P	Hydroxyl from saccharides, phosphoprotein	[74, 77]