ABSTRACT
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Due to the fact that the Bacteria and Archaea are difficult to distinguish on the
basis of their morphology by microscopy, they have traditionally been
grouped together under the heading prokaryotes. However, after the advent
of molecular phylogenetics, we now know that the Bacteria and Archaea are
as different from each other as they are from the Eukarya (formerly called
eukaryotes). Chapter 2 has examined these issues in more detail. Given the
differences between the Bacteria and Archaea, the consensus is growing that
the term prokaryote should eventually be phased out of the literature.
However, in the meantime this term is still used out of convenience, and we
will also use it in this chapter. Nevertheless, the reader should keep in mind
that bacteria and archaea represent two clearly distinct divisions of life. In this
chapter, we will primarily be discussing the bacteria in soil, since we know
much more about this group than about the soil archaea; however, when
information is available, the latter will also be discussed.
