Diversity of streptomycetes among specific Greek terrestrial ecosystems

The diversity of streptomycetes isolated from different Greek terrestrial e cosystems using phenotypic identification, and the relationship between the number of species and the number of isolates as a diversity index, was stu died. A total of 344 Streptomyces strains have been isolated and identified from diverse sites in the Greek territory, such as heavily disturbed agric ultural areas and preserved forest areas, and from specific rhizosphere eco systems. 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 habita ts. On the other hand, there were cluster groups that appeared in only one or two habitats, such as Strep. griseoflavus, Strep. rimosus, Streptovertic illium blastmyceticum, Nocardia mediterranea and Strep. fulvissimus. The di versity indices among the different cluster groups of each sampling area in dicated that the different habitats can be sub-divided into two main groups : rhizosphere habitats and non-rhizosphere habitats, showing that the rhizo sphere is one of the most important factors which determines the population structure of a specific soil area.