Ecology of the Streptomycetes Flora in the Desert Soil of Kuwait

Abstract

Summary The distribution of the streptomycetes flora in four plant communities in the desert of Kuwait was investigated. The results show that the counts of actinomycetes vary considerably with the community. Maximal counts of 1156 × 10 4 /g soil were found in the rhizosphere of Rhanterium epapposum . The saline habitat, represented by Salicornia herbaceae and Nitraria retosa communities, was very poor in total viable bacteria and actinomycetes. From Rhanterium, Cyperus , and Salicornia communities, 256 actinomyctes isolates were obtained; they were identified as Streptomyces (254), Streptoverticillium (one isolate) and Nocardia (one isolate). The Streptomyces isolates belonged to seven color series. The dominant one was the Grey series (72%), while the Green series was rarely recorded. The Red series was more frequent (14%) than the Yellow, Blue and Violet series. Species identification of the 254 Streptomyces isolates indicated the presence of 65 Streptomyces species in the desert of Kuwait. S. olivaceus was comparatively frequent (12.2%), followed by S. albogriseolus (8.7%), S. resistomycificus (5.5%), S. lydicus (4.7%), S. echinatus and S. plicatus (each 4.3%) and S. fumanus (3.9%). Other species represented 0.4–3.1%. Each community was characterized by the presence of particular species that were found in no other community. In the roots of the different plants investigated particular Streptomyces species were found. This was also observed with different non-rhizosphere soils of different communities. Some unidentifiable Streptomyces species were characterized by wedged spore surfaces distinct from smooth and warty surfaces, while other species showed peculiar morphological characteristics when growing on glycerol asparagine agar.