Physicochemical impact of bioactive terpenes on the microalgae biomass structural characteristics

This study aimed to evaluate the functionality of bioactive terpenes on Spirulina (Arthrospira platensis; AP) and Chlorella (Chlorella vulgaris; CV) biomasses. The two microalgae species were treated with 0.01%, 0.05%, and 0.1% of thymol (THY), trans-cinnamaldehyde (TC), menthol (MEN), and vanillin (VAN). Raman microspectroscopy (RMS) was correlated with other physicochemical methods to confirm their functional mechanisms. In results, THY (0.1%) decreased (P < 0.05) RMS intensity at 1196 cm-1 that represents the protein's secondary amines wavenumber. Also, VAN (0.1%) decreased significantly A. platensis alpha-helix to 16.60 +/- 0.52% compared to the control with 19.83 +/- 0.32%. While, 0.1% TC increased (P < 0.05) the viscosity to 2.52 +/- 0.61 Pa.s. This work demonstrated that terpenes could differently affect the physicochemical structure of microalgae biomass. The RMS's uniqueness comes from its ability to evaluate the functionality of terpenes during microalgae cultivation. Besides, chemometrics led to focus on the most important variances.

Automated summary

This study evaluated the functionality of bioactive terpenes on Spirulina and Chlorella biomasses. The results showed that terpenes can affect the physicochemical structure of microalgae biomass differently, with thymol and vanillin showing significant effects, while trans-cinnamaldehyde increased viscosity. The unique capability of Raman microspectroscopy in evaluating terpenes during microalgae cultivation was demonstrated in this work.