In vivo prediction of the nutrient status of individual microalgal cells using Raman microspectroscopy

An in vivo method for predicting the nutrient status of individual algal cells using Raman microspectroscopy is described. Raman spectra of cells using 780 nm laser excitation show enhanced bands mainly attributable to chlorophyll a and beta-carotene. The relative intensities of chlorophyll a and beta-carotene bands changed under nitrogen limitation, with chlorophyll a bands becoming less intense and beta-carotene bands more prominent. Although spectra from N-replete and N-starved cell populations varied, each distribution was distinct enough such that multivariate classification methods, such as partial least squares discriminant analysis, could accurately predict the nutrient status of the cells from the Raman spectral data.