Actinomycete Flora in Soil of Differently Degraded Alpine Grasslands in Three River Source Area
三江源地区不同退化程度草地的土壤放线菌区系

The quantity and diversity of soil actinomycetes were compared between grasslands with different degradation degree in Three River Source area, using different isolation methods and media. In this area, 178 strains were isolated from 5 soil samples collected, and were classified into 7 recognized genera based on phenotypic characteristics and 16S rRNA gene sequences, including Micromonospora, Promicromonospora, Nocardia, Pseudonocardia, Actinoplanes, Kribbella and Streptomyces. Isolates of Streptomyce were further divided into 7 phenotypic groups. Larger quantity and higher diversity of actinomycetes were found in soil from lightly degraded steppe than in soil from heavily degraded steppe, and were also found in soil from Stipa purpurea alpine steppe than in soil from Kobresia pygmaea alpine meadow which, however, possessed higher diversity of streptomycetes than the former. The results indicate a negative correlation between degradation degree of alpine grasslands and quantity and diversity of the soil actinomycetes.