A REVIEW OF ISSUES RELATED TO THE QUANTIFICATION OF BACTERIA FROM THEPHYLLOSPHERE

Quantification of the size of epiphytic bacterial populations and char acterization of their composition involves definition of a sampling st rategy in time and space, the choice of methods for liberating the bac teria from the leaf surface and for recovering them for subsequent det ermination of the number of viable or culturable cells. This literatur e review focuses on some of the issues related to these choices. After briefly reviewing the different types of epiphytic colonizers we cons ider the biological, methodological, and statistical consequences of t he choice of the sampling unit and of the spatial and temporal variabi lity of population size and composition for epiphytic bacteria. The di fferent methods available for the detection and enumeration of natural ly occurring microorganisms in the phyllosphere are discussed. Advanta ges and drawbacks of each are described in this review designed as a ' hands-on' guide.