Dunaliella salina is able to produce simultaneously several valuable compounds (such as lipids, carotenes and functional proteins) within the biorefinery concept. However due to the lack of rigid cell wall, this microalgae can easily disrupt during harvesting, losing valuable compounds to the saline water, affecting the downstream processing. Therefore, the development of non-invasive tools able to monitor cell concentration and integrity in real-time, can assist the development of harvesting methodologies. In the present work, a monitoring approach was developed based on two-dimensional (2D) fluorescence spectroscopy. Mathematical analysis of the monitoring data involved the use of Principal Component Analysis (PCA) and Projection to Latent Structures (PLS) modelling. For green D. salina, the models developed for prediction of cell number and percentage of viability captured 90.6% and 86.3% of variance, respectively. Both models have R2 of 0.8 and 0.9, respectively for validation and training. Similar values were found for the prediction of cell number when using data from growth kinetics and harvesting combined. Orange D. salina rupture was also successfully modelled with 95% of variance captured and R2 of 0.9 for both training and validation. The combined approach using 2D fluorescence spectroscopy and the mathematical analysis proved to have the potential to monitor D. salina during cell growth and harvesting within a biorefinery concept.
Sá, M., Monte, J., Brazinha, C., Galinha, C. F., & Crespo, J. G. (2017). 2D Fluorescence spectroscopy for monitoring Dunaliella salina concentration and integrity during membrane harvesting. Algal Research, 24, 325–332. doi:10.1016/j.algal.2017.04.013
The authors would like to acknowledge the financial support provided by the European KBBE FP7 project “D-Factory”, King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under award no. OSR-2016-CPF-2907-05, and also the FCT, Portugal, for the Post-Doctoral fellows grants SFRH/BPD/95864/2013 of Claudia Galinha (orcid=“0000-0003-0045-2528”) and SFRH/BPD/79533/2011 of Carla Brazinha, and PhD Fellow grant SFRH/BD/108894/2015 of Marta de Sá. A special thanks to the company A4F – Algae for future (Portugal), for sharing their extensive knowledge and supplying all the biomass needed to develop this work, as well as NBT Ltd (Israel) and The Marine Biological Association (Devon, UK).