DIVERSITY OF SOIL ACTINOMYCETES IN YUNNAN, CHINA

Since 1978, about 4,200 soil samples have been collected from 22 selec ted areas of various vegetational and climatic types throughout the pr ovince of Yunnan, Actinomycetes of 29 genera were isolated by the meth ods employed. The correlations between diversity and climate were grou ped into tropical, subtropical plateau, cool temperate mountain, and s nowy mountain types. Actinomycete populations of the first two types w ere more complex than were the other ones, Correlations between actino mycete diversity and vegetation were also attempted. Six types of vege tation were compared. The diversity of actinomycetes was greatest in s oil samples of a primeval forest, with an average of 9.0 genera isolat ed, followed by secondary forest and vegetable farmland samples, with averages of 6.7 and 6.5 genera isolated, respectively, The upper limit for the occurrence of thermophilic actinomycetes is about 3,500 m abo ve sea level in Yunnan. Psychrophilic actinomycetes were isolated at u p to the same altitude, In addition, the drier and poorer the soil was and the cooler the climate was, the lower the count of actinomycetes was and the higher the percentage of streptomycetes observed was, The genus Streptomyces appears to be the most important in ecological func tion. it represents up to 90% of all soil actinomycete diversity in Yu nnan and is likely an important characteristic of the soil actinomycet e population.