Abstract: We studied the changes of structural characteristics before and after kaolinite and montmorillonite participated in the liquid shake flask culture of lignin inoculated the suspension of mixed strains during the culture period of 110 d by using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Xray diffraction (XRD). The results show that when kaolinite is involved in the microbial transformation of lignin, the structural water is unbalanced, the edge bond breaking makes its surface accumulate negative charge, the surface hydration layer forms hydrogen bonds at multiple points, which increases the stretching vibration of association —OH, the edge and the base octahedron O of Al—OH all have dehydroxylation, which makes the deformations of tetrahedral and octahedral sheets and generate a large number of broken bonds, resulting in weakening of the vibrational frequencies of Si—O,Si—O—Al and Si—O—Si, and the crystal structures change to longrange disorder, but there is no phase change. Montmorillonite is an expanding mineral, which is hydrophilic inside. After the liquid shaking flask culture, the crystal water shrinks to destroy the interlayer structures and increase the surface roughness. After participating in the microbial transformation of lignin, the extracellular polymers released by the microorganism forms a hydrogen bond with the surface functional group of the montmorillonite, which reduces the total amount of the hydroxyl groups and crystal H2O in the interlayer and lattice, increases the vibrational frequencies of Si—O,Mg—Al—OH and Fe—O—Si bonds (or Mg—O—Si bond), and the characteristic diffraction peak at low wave disappears.

Key words: clay mineral, kaolinite, montmorillonite, lignin, humification (mechanism)