[In Vivo Study of Chitin in Fungal Hyphae Based on Confocal Raman Microscopy].

Chitin is an important structural polysaccharide of fungal cell wall. In this paper, aerial hyphae of Colletotrichum camelliae Massee was first studied by confocal Raman microscopy in vivo. Firstly, the optimal experimental parameters of hyphae for collecting the Raman spectra were determined, and the typical Raman spectra of hyphae, chitin standard and background were acquired. By comparing analysis, characteristic peaks of chitin were found in hyphae. Then, a region of interesting on hyphae was selected for Raman scanning. Through principal component analysis, the Raman signal of hyphae and background in the scanning area can be separated clearly. Combined with loading weight plot, two main characteristic peaks of hyphae were obtained, 1 622 cm(-1) was belong to chitin and 1 368 cm(-1) was assigned to pectic polysaccharide. Finally, two and three dimension chemical images of fungal hyphae were realized based on Raman fingerprint spectra of chitin in a nondestructive way.

[Revealing the Cell Structure and Formation of Bamboo with Confocal Raman Microscopy].

Parenchyma cell (PAC), transition tissue between parenchyma cell and fiber cell (TC) and fibre cell (FC) of bamboo were studied by confocal Raman microscopy in this paper. Partial least squares regression was applied to establish a quantitative differentiation model for the three types of cells. The result showed that the determination coefficients (R²) of calibration and validation were respectively 0.810 and 0.800, and the root mean square error (RMSE) were respectively 0.323 and 0.332. What's more, three raman bands of 1,095, 1,319 and 1,636 cm⁻¹, verified to the characteristic peaks of pectin, hemicellulose and lignin, were found to be the important bands for the differentiation. Subsequently, these three raman bands were used to establish a multiple linear regression (MLR) model, and the determination coefficients (R²) of calibration and validation of the model were respectively 0.644 and 0.643, and the root mean square error (RMSE) were respectively 0.442 and 0.443. This result showed that there existed obvious difference among the three types of cells in these three raman bands. Finally, the raman spectral signal processed by wavelet transform to eliminate baseline were used to chemical imaging analysis. These results showed a rather large microfibril angle between cellulose fibrils and fibre axis, which contributed to higher modulus and hardness of cells. Hemicellulose and cellulose have similar distribution in the raman chemical image, due to the connection of hemicellulose and cellulose microfiber through hydrogen bond and the closely combination under the action of van der Waals force. The cell corners (CC) and compound middle lamella (CML) were heavily lignified, and a gradual decrease of lignification from the outer layer to the inner layer of the three cells indicate that lignification was first occurred at the CC and CML, and the lignification was not fully completed.