title: Sorting cells of the microalga Chlorococcum littorale with increased triacylglycerol productivity.
abstract: BACKGROUND
  Despite extensive research in the last decades, microalgae are still only economically feasible for high valued markets. Strain improvement is a strategy to increase productivities, hence reducing costs. In this work, we focus on microalgae selection: taking advantage of the natural biological variability of species to select variations based on desired characteristics. We focused on triacylglycerol (TAG), which have applications ranging from biodiesel to high-value omega-3 fatty-acids. Hence, we demonstrated a strategy to sort microalgae cells with increased TAG productivity.
  
  
  RESULTS
  1. We successfully identified sub-populations of cells with increased TAG productivity using Fluorescence assisted cell sorting (FACS). 2. We sequentially sorted cells after repeated cycles of N-starvation, resulting in five sorted populations (S1-S5). 3. The comparison between sorted and original populations showed that S5 had the highest TAG productivity [0.34 against 0.18 g l(-1) day(-1) (original), continuous light]. 4. Original and S5 were compared in lab-scale reactors under simulated summer conditions confirming the increased TAG productivity of S5 (0.4 against 0.2 g l(-1) day(-1)). Biomass composition analyses showed that S5 produced more biomass under N-starvation because of an increase only in TAG content and, flow cytometry showed that our selection removed cells with lower efficiency in producing TAGs.
  
  
  CONCLUSIONS
  All combined, our results present a successful strategy to improve the TAG productivity of Chlorococcum littorale, without resourcing to genetic manipulation or random mutagenesis. Additionally, the improved TAG productivity of S5 was confirmed under simulated summer conditions, highlighting the industrial potential of S5 for microalgal TAG production.
authors: Wageningen UR, Bioprocess Engineering, AlgaePARC, P.O. Box 16, 6700 AA Wageningen, The Netherlands.
authors: Iago Teles Dominguez
authors: IT
authors: Cabanelas
authors: Wageningen UR, Food and Biobased Research, AlgaePARC, Wageningen, The Netherlands.
authors: Mathijs
authors: M
authors: van der Zwart
authors: Wageningen UR, Food and Biobased Research, AlgaePARC, Wageningen, The Netherlands.
authors: Dorinde M M
authors: DM
authors: Kleinegris
authors: Wageningen UR, Bioprocess Engineering, Wageningen, The Netherlands ; Faculty Biosciences and Aquaculture, Nord University, Bodø, Norway.
authors: René H
authors: RH
authors: Wijffels
authors: Wageningen UR, Bioprocess Engineering, Wageningen, The Netherlands.
authors: Maria J
authors: MJ
authors: Barbosa
keywords: Chlorococcum littorale; Fluorescence assisted cell sorting (FACS); Lipid productivity; Microalgae; Strain improvement