Enumeration of Microalgal Cells - Biotechnological Applications of Microalgae - page 45

4 Enumeration of

Microalgal Cells

Taurai Mutanda and Faizal Bux
Institute for Water and Wastewater Technology
Durban University of Technology
Durban, South Africa

CONTENTS
4.1 Introduction .................................................................................................... 45
4.2 Sampling and Culturing Microalgae .............................................................. 46
4.3 Microalgal Preservation .................................................................................. 46
4.4 Enumeration Methods ..................................................................................... 47
4.4.1 Spectrophotometric Analysis .............................................................. 47
4.4.2 Gravimetric Analysis .......................................................................... 47
4.4.3 Counting Chambers ............................................................................ 48
4.4.4 Flow Cytometry .................................................................................. 48
4.5 Conclusion ...................................................................................................... 48
Acknowledgments .................................................................................................... 50
References ................................................................................................................ 50

4.1 INTRODUCTION
The estimation of a microalgal population size is no easy task due to the micro-
scopic size of the cells. Consequently, it is impossible to physically count them
with the naked eye. The size of microalgae falls within the size of other microbes
(e.g., bacteria) and, as a result, most of the methods used for microbial cell counting
are also applicable to microalgae. In general, conventional microbiological proto-
cols are available and are sufficient for cell enumeration despite the proliferation
of modern and advanced techniques. It is recommended that the researcher choose
a method after assessing the costs involved because some of the latest methods
require very sophisticated and expensive equipment.
According to Caron et al. (2003), “the identification and enumeration of micro-
organismal species in natural aquatic assemblages is an essential prerequisite for
ecological studies of these populations.” Effective ecological studies of populations
of colonial freshwater phytoplankton species are hampered by a lack of methods for
cell enumeration (Box, 1981). Closely related microalgal groups must be accurately
distinguished, and this is very crucial when these species pose health and environ-
mental risks (Caron et al., 2003).

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