High-throughput phenotyping of microalgae using hyperspectral imaging

Authors: Milán Szabó1, Zalán Tóth-Nyári1,2, Zoltán Szabó1,2, Miklós Hovári1, László Sass1, Priyanka Patil1,2, Gábor Patyi1, Imre Vass1

Affiliations:

1Institute of Plant Biology, HUN-REN Biological Research Centre, Szeged, Hungary

2Doctoral School of Biology, University of Szeged, Hungary

Microalgae are key players of our ecosystems. Due to their photosynthetic activity, they play a tremendous role in atmospheric CO2 fixation. In biotechnology and agriculture, they are important sources of high value compounds, such as carotenoids, polyunsaturated fatty acids and nutraceuticals. To reveal the full potential of microalgae, high-throughput monitoring systems are imperative to monitor their productivity and stress responses. Hyperspectral imaging is a reflectance-based phenotyping method, which is used for remote sensing as well as laboratory scale investigation of physiological and biochemical properties of various organisms from cellular to ecological levels. Although hyperspectral imaging has become a high-throughput tool in agriculture, ecology and plant science, its potential and application remain far less advanced in microalgae. Utilizing the advantages of hyperspectral sensing to potentially identify non-invasive physiological and phenotypic traits, we demonstrate that hyperspectral indices can be obtained in microalgae in a wide range of chlorophyll content of single species as well as in algal mixtures. We also identified spectral signatures that indicate pigment loss (phycocyanin in Synechocystis sp.) or accumulation of valuable carotenoids (astaxanthin in Haematococcus sp.) under stress conditions. Furthermore, several species of microalgae with a diverse pigment composition (e.g. Nannochloropsis sp., the coral endosymbiont algae Symbiodiniaceae) have been analyzed to define taxon-specific spectral markers. In addition, we established single-cell phenotyping methods to characterize photosynthetic activity, morphological and cell cycle analysis using microfluidic tools. These approaches open new avenues for comprehensive understanding of the benefits of microalgae for applied research, with prospects for aquaculture applications as well.