Fig. 7

Fourier-transform infrared (FTIR) spectra of tobacco stalks treated with strain LXX12 at 0, 7, 14, and 28 days. The peak at 3100–3254 cm⁻¹ associated with the -OH stretching vibration is enhanced, indicating the formation of alcohol/phenolic products from lignin degradation. The peaks at 1652 cm⁻¹ (C=C/C=O), 1423 cm⁻¹ (–CH₂), and 616 cm⁻¹ (aromatic ring) point to the gradual breakdown of lignin, with the accumulation of aromatic and aldehyde/ketone compounds, and the release of aliphatic compounds. The weakening of the O = C–C peak at 1235 cm⁻¹ suggests the dissociation of the hemicellulose-lignin complex, while the enhancement of the Si–O and polysaccharide C–O peaks at 1109 cm⁻¹, and the flattening of the C-O/C-C peaks at 1035 cm⁻¹ reflect the breakdown of the silicate layer, exposing and degrading cellulose/hemicellulose to produce small organic molecules.