Detecting Phytoplankton Cell Viability Using NIR Raman Spectroscopy and PCA

Area of Science:

• Marine biology
• Spectroscopy
• Biotechnology

Background:

• Raman spectroscopy offers potential for monitoring phytoplankton but faces challenges with pigment interference and spectral complexity.
• Visible detection methods are limited in pigment-rich biological samples.
• Developing reliable in situ methods for phytoplankton analysis is crucial for marine ecosystem monitoring.

Purpose of the Study:

• To develop a reliable method for assessing phytoplankton cell viability using Raman spectroscopy.
• To overcome the limitations of visible detection methods in pigment-rich phytoplankton.
• To identify spectral features indicative of cell viability across different phytoplankton species.

Main Methods:

• Utilized 1064 nm confocal Raman spectroscopy, a near-infrared (NIR) approach.
• Applied multivariate statistical analysis, including principle component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA).
• Investigated cell viability in diatom (Chaetoceros muelleri) and haptophyte (Diacronema lutheri, Tisochrysis lutea) species.

Main Results:

• The combined NIR Raman spectroscopy and multivariate analysis approach minimized fluorescence background.
• Successfully differentiated between viable and nonviable phytoplankton cells across species.
• Identified characteristic spectral shifts in carotenoid bands (1527 and 1158 cm⁻¹) as key indicators of cell death.

Conclusions:

• This combined technique provides a robust method for monitoring phytoplankton viability in situ.
• The approach overcomes previous limitations associated with pigment interference and spectral complexity.
• Spectral changes in carotenoids are reliable biomarkers for phytoplankton cell viability assessment.