Linear Discriminant Analysis of Single-Cell Fluorescence Excitation Spectra of Five Phytoplankton Species
Linear discriminant analysis (LDA) of single-cell fluorescence excitation spectra (λem = 680 nm) for five species of marine phytoplankton was used to determine whether intra-species variation among single cells precluded discrimination among species. Single-cell
spectra were recorded in an optical trap with a custom-built spectral fluorometer. For nitrogen (N)-replete cells, separation of all five species (Emiliania huxleyi, a coccolithophore, Thalassiosira pseudonana, a diatom, Dunaliella tertiolecta, a chlorophyte, Amphidinium
carterae, a dinoflagellate, and Rhodomonas salina, a cryptophyte) was possible using only a portion of the excitation spectra (570‐610 nm). This wavelength region gave perfect classification of species with a minimum Fisher ratio of 62. For four species (E. huxleyi,
T. pseudonana, D. tertiolecta, and A. carterae), variations in fluorescence excitation spectra as cells were starved of N did not impact the classification process adversely within the chosen spectral window. R. salina cells grown with and without N showed significant
differences in their fluorescence excitation spectra but could still be classified if a different spectral window (490‐570 nm) was used. Overall, we conclude that intra-species variation among single-cell fluorescence excitation spectra does not preclude discrimination among species.
Document Type: Research Article
Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 29208, USA
Department of Biological Sciences, University of South Carolina, Columbia, South Carolina
Publication date: January 1, 2012
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