Fig. 7

FTIR analysis of yeast cell wall modifications during lipid accumulation. The second derivatives of the FTIR spectra of yeast cells are reported in the spectral range comprised between 1200–950 cm⁻¹, mainly ascribable to the absorption of cell wall carbohydrates. Spectra of control (a) and oleaginous yeasts C. curvatus (b) R. toruloides (c), and L. starkeyi (d) are displayed at time 0 and at 144 h of growth in crude and pure glycerol. For comparison, the second derivative spectra have been normalized at the tyrosine band at ~1516 cm⁻¹