三江源地区不同退化程度草地的土壤放线菌区系

用不同分离方法,对三江源地区不同退化程度草地土壤放线菌的数量和多样性进行了比较.从5份土样中共分离放线茵178株,根据表型特征和16S rRNA基因序列分析,分别归入7个已知属:小单孢菌属(Micromonospora)、原小单孢菌属(Promicromonospora)、诺卡氏菌属(Nocardia)、假诺卡氏菌属(Pseudonocardia)、游动放线菌属(Actinoplanes)、韩国生工茵属(Kribbella)和链霉菌属(Streptomyces).其中链霉菌属分离菌株可归入7个表型类群.发现轻度退化高寒草原的土壤放线菌数量,丰度和多样性高于重度退化高寒草原;针茅高寒草原的土壤放线菌数量和多样性高于蒿草高寒草甸,而其中链霉菌的种类低于后者.表明高寒草地的退化程度与其中土壤放线茵的数量和多样性呈负相关.

Actinomycete Flora in Soil of Differently Degraded Alpine Grasslands in Three River Source Area

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.