Section 1 Phytoplankton

**3**

**Chapter 1**

**Abstract**

**1. Introduction**

of photosynthetic cells [4–6].

*Natalia Grigoryeva*

Self-Fluorescence of

Photosynthetic System: A

Powerful Tool for Investigation of

It is well-known that photosynthetic cells of various microalgae species display distinct fluorescent properties. The efficiency of self-fluorescence excitation and emission at different wavelengths depends on the structure of photosynthetic system and particularly on the structure of antenna complex of specific strains. The peculiar structure of blue-green algae light-harvesting complex allows to discriminate and classify known and new cells up to species/strain level by means of microscopic spectroscopy. In this chapter, a novel fluorescent spectroscopic technique for microalgae species discrimination will be presented. This method is based on a special data processing of a set of fluorescent spectra, obtained from a single photosynthetic cell of microalgae, particularly from cyanobacterial cells. According to the presented technique, single-cell self-fluorescence spectra are recorded by means of confocal laser scanning microscopy (CLSM), and data processing is conducted via

Microalgal Biological Diversity

linear discriminant analysis (LDA) and artificial neural networks (ANN).

fluorescence, microscopic spectroscopy, artificial neural networks

cal state of cyanobacterial cultures and natural communities.

**Keywords:** microalgae, cyanobacteria, photosynthetic system, biological diversity,

Cyanobacteria are the most ancient photosynthetic microorganisms on Earth. Nowadays, cyanobacteria are one of the most widespread organisms in nature, and the ecological aspect in their investigation is quite valuable. On the other hand, thousands of strains belonging to different species are cultivated in biolaboratories all over the world for different cyanobacterial biotechnological applications such as biofuel cells, food production, pharmaceuticals, fertilizers, etc. [1–3]. Thus the noninvasive spectroscopic methods are quite requisite for monitoring of physiologi-

It is well-known that the analysis of self-fluorescence of photosynthetic system is a powerful noninvasive tool for investigation of microalgae in vivo. It reports on the energy transfer and trapping and, thus, reflects the metabolic mechanisms in photosynthetic cells and their photosynthetic efficiency. The detected selffluorescence finally reflects the diversity in morphological and physiological states
