Microalgal swimming signatures as indicators of neutral lipids production across growth phases

TL;DR

This study shows that swimming behavior of microalgae correlates with lipid accumulation during growth phases, offering a non-invasive way to optimize harvest timing for biofuel and metabolite production.

Contribution

It introduces the use of swimming signatures as indicators of lipid content and growth phase in microalgae, a novel approach for cultivation monitoring.

Findings

Swimming speed peaks during maximum lipid accumulation.

Swimming trajectories indicate growth phases and lipid levels.

Swimming signatures can guide harvest timing for biofuel yield.

Abstract

Microalgae have been shown as a potential bioresource for food, biofuel, and pharmaceutical products. During the growth phases with corresponding environmental conditions, microalgae accumulate different amounts of various metabolites. We quantified the lipid accumulation and analyzed swimming signatures (speed and trajectories) of the motile green alga, Dunaliella primolecta, during the lag-exponential-stationary growth cycle at different nutrient concentrations. We discovered significant changes in neutral lipid content and swimming signatures of microalgae across growth phases. The timing of the maximum swimming speed coincided with the maximum lipid content and both maxima occurred under nutrient stress at the stationary growth phase. Furthermore, the swimming trajectories of microalgae signal the growth phase and corresponding intracellular lipid accumulation. Our results provide the potential exploitation of microalgal swimming signatures as indicators for the cultivation conditions and the timing of microalgal harvest to maximize the lipid yield for biofuel production. The findings can also be implemented to explore the production of food and antibiotics from other microalgal metabolites with low energy cost.