How growth conditions of Euglena gracilis cells influence cellular composition as evidenced by Fourier transform infrared spectroscopy and direct infusion high-resolution mass spectrometry

Abstract

This study aims to assess the influence of growth and culture conditions of the Euglena gracilis protist on the cellular chemical composition. Fourier transform infrared spectroscopy (FT-IR) and direct infusion Orbitrap electrospray ionization mass spectrometry (ESI-MS) were used in tandem for confirmation of functional groups, and to decipher the normalized percentage abundances of compound classes, molecular species, and aromaticity and oxygenation within each growth condition. Abundances of molecular species and compound classes varied with growth and culture conditions. No major differences in the qualitative FT-IR-based screening of functional groups were found between growth conditions. This contrasts with ESI-MS-based results where polyphenols, carbohydrate, and condensed aromatic compounds were the most abundant in dark-grown conditions with glucose supplementation, revealing the differences in physiological states of the cell in different growth conditions. Dark-grown conditions promoted CHO molecular species while light-grown conditions favored CHON, CHOS, and CHONS molecular species. The dark-grown exponential E. gracilis cells grown in glucose-supplemented media showed the greatest normalized abundances of aromatics, carbohydrate, polyphenols, and protein, which are compound classes typically involved in metal binding.