Diversity of streptomycetes among specific Greek terrestrial ecosystems

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.