**Author details**

The universality of the considered technique makes it possible to use it for investigation of any phytoplankton species irrespective of their habitat or cultivation. Utilizing data from several fluorescence spectra, instead of one, results in more fingerprint information which leads to the taxonomic differentiation on a finer scale. Classification procedure, presented here, was carried out by means of statistical analysis on the base of mathematical characteristics of intrinsic fluorescence spectra of living single cells; therefore, it is free from usual subjectivity, which can occur while using methods of direct optical microscopy. Moreover, formalization of data processing gives a wide opportunity for automating of the classification procedure of cyanobacterial strains in field samples, while on-line monitoring of water bodies is conducted. Undoubtedly, the data set should be expanded to include more species and phytoplankton classes/divisions, grown under different nutrient and light conditions. However, this work already demonstrates the potential of the discrimination of phytoplankton classes by fluorescence microscopic spectroscopy. This work lays the foundation for determining cyanobacterial abundance by direct fluorescence measurement of sea- and freshwater. Combining the knowledge of phytoplankton structure along with taxon-specific measurements of photosynthetic activity and biochemical cell composition, can lead to new models which increase the

In this chapter, the most powerful CLSM method for investigation of cyanobacteria—the fluorescence microscopic spectroscopy—was presented. This method allows to study living cyanobacterial cells via noninvasive and nondestructive technique and obtained in-vivo information about weak variations in single-cell functioning. It should be noted that CLSM provides some other interesting techniques, which can give deep insight into physiological processes that rules cyanobacterial life, such as FRAP [68–69, 105, 106] and hyperspectral microscopy [44]. FRAP is used to measure the mobility of phycobilisomes in intact cyanobacterial cells and hyperspectral microscopy helps to determine pigment localization and distribution in living cyanobacterial cells. Moreover, several time-dependent techniques for investigation of the dynamic properties of photosynthetic apparatus of cyanobacteria, such as

A limited number of examples, presented here, of possible fluorescence microscopic spectroscopy implementation (e.g., the investigation of biological diversity and monitoring of physiological state of cyanobacterial cultures) can significantly rise an effectiveness of the routine procedures in environmental monitoring and industrial culture production. Confocal microscopic spectroscopy gives a unique opportunity to introduce automation into these processes. On the other hand, the indirect application of the presented results of the single-cell spectroscopic investigations can give a new information to improve remote sensing control. Spectral information recorded by satellite-carried sensors is already used for mapping of algae distribution, and due to the high frequency of data collection provides a database for estimation of phytoplankton dynamics over large areas [107]. Presented investigation gives an opportunity to control also cyanobacterial communities. The elaborated technique can be supported with algorithm that includes a new mathematical fitting strategy which automatically can

PAM, can be implemented at a single-cell level by means of CLSM.

reliability of on-line monitoring.

34 Cyanobacteria

**4. Conclusion and outlook**

Natalia Grigoryeva<sup>1</sup> \* and Ludmila Chistyakova<sup>2</sup>

\*Address all correspondence to: renes3@mail.ru

