Fourier Transform Infrared Spectrometry Detection of Phaeodactylum tricornutum Biomacromolecules in Response to Environmental Changes

Abstract

Environmental factors play an important role in the lipid, protein, and carbohydrate compositions of microalgae, wherein temperature and light are key influencing factors. Fourier transform infrared (FTIR) spectrometry was used in this study to detect biomacromolecules in Phaeodactylum tricornutum cells under different temperatures (10, 15, 20, and 25 °C) and different illumination conditions (1000, 2000, 3000, and 4000 lx) to study the corresponding changes in lipid, protein, and carbohydrate contents. Results indicate that the biomacromolecule content at different temperatures has different patterns. Specifically, the patterns at 15 and 25 °C are similar to each other and the contents accumulate with extended culture time. However, the pattern at 20 °C is different. The carbohydrate and protein contents peaked during the early stage of the exponential phase, whereas lipid accumulation lagged behind the former two, peaking during the middle of the culture stage and then decreasing. Lipid content was analyzed by transmission electron microscopy (TEM), which revealed that the highest lipid content was observed at 15 °C. Results also show that all of the lipid, protein, and carbohydrate contents in cells were the highest when the illumination was at 2000 lx and that the contents decreased with increasing illumination. By using FTIR, less samples were needed as compared to the traditional chemical quantitative detection methods. Moreover, the relative content changes of various biomacromolecules during the growth of P. tricornutum could be accurately determined by a single detection, thereby providing a new technique for the further study of metabolic mechanisms.