Investigating the Potential of Ion Mobility-Mass Spectrometry for Microalgae Biomass Characterization

Algae
biomass is formed by an extremely complex set of metabolites,
and its molecular characterization has been very challenging. We report
the characterization of microalgae extracts via traveling wave ion
mobility–mass spectrometry (TWIM-MS) by two different analysis
strategies. First, the extracts were analyzed by direct infusion electrospray
ionization (ESI) with no previous chromatographic separation (DI-ESI-TWIM-MS).
Second, the samples were screened for metabolites and lipids using
an untargeted high-throughput method that employs ultrahigh-performance
liquid chromatography (UHPLC) using data-independent analysis (DIA)
– MSE (UHPLC-HDMSE). Sixteen different
microalgae biomasses were evaluated by both strategies. DI-ESI-TWIM-MS
was able, via distinct drift times, to set apart different classes
of metabolites, with the differences in the profiles of each microalga
readily evident. With the UHPLC-HDMSE approach, 1251 different
compounds were putatively annotated across 16 samples with 210 classified
as lipids. From the normalized abundance for each annotated compound
category, a detailed profiling in terms of metabolites, lipids, and
lipid classes of each sample was performed. The reported workflow
represents a powerful tool to determine the most suitable biotechnological
applications for a given alga type and may allow for real-time monitoring
of the algae composition distribution as a function of growth conditions,
feedstocks, and the like. The determination of collision cross section
results in improved confidence in the identification of triacylglycerols
in samples, highly applicable to biofuels production. The two analysis
strategies explored in this work offer powerful tools for the biomass
industry by aiding in the identification of ideal strains and culture
conditions for a specific application, saving analysis time and facilitating
identification of a large number of constituents at once.