1. Introduction
Community and diversity surveys of bacteria have for
nearly 10 years focused on the phylogenetic diversity of
bacteria in the environment. However, species composition based on 16S rRNA analysis only provides marginal information on communities and certain metabolic
groups. An exciting direction in molecular ecology is the
analysis of genes encoding important functions for the
ecosystems. The analysis of functional diversity and its
physiological dynamics is essential for improved understanding of the microbial ecology and biogeochemistry of different environments. Generally, functional
genes have more sequence variation than the relatively
conserved 16S rRNA genes. They can therefore be exploited as biomarkers to discriminate between closely
related but ecologically different populations [1].
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