The diversity of streptomycetes isolated from different Greek
terrestrial ecosystems using phenotypic identification, and the
relationship between the number of species and the number of isolates as
a diversity index, was studied. A total of 344 Streptomyces strains have
been isolated and identified from diverse sites in the Greek territory,
such as heavily disturbed agricultural areas and preserved forest areas,
and from specific rhizosphere ecosystems. According to phenotypic
identification, these strains belonged to 19 different cluster groups
with a Willcox probability > 0.8. Streptomyces cyaneus, Strep.
albidoflavus, Strep. diastaticus and Strep. exfoliatus were the most
common cluster groups isolated from at least six different habitats. On
the other hand, there were cluster groups that appeared in only one or
two habitats, such as Strep. griseoflavus, Strep. rimosus,
Streptoverticillium blastmyceticum, Nocardia mediterranea and Strep.
fulvissimus. The diversity indices among the different cluster groups of
each sampling area indicated that the different habitats can be
sub-divided into two main groups: rhizosphere habitats and
non-rhizosphere habitats, showing that the rhizosphere is one of the
most important factors which determines the population structure of a
specific soil area