Culture-dependent method was employed to evaluate the diversity of culturablebacteria and actinobacteria in tissues of medicinal plant samples,desert soil crusts and the specific habitat of cyanoHABs fresh water.As a result,the bio-diversity of bacteria and actinobacteria was demonstrated,as well as a number of hereto unrecognized bacterial and actionbacterial taxa were discoved.Comparison study on the endophyts from medicinal plants showed that there was no direct relationship of the endophytics from medicinal plants with the host plants in the sole carbon source utilization,fermentation of carbon sources to produce acid and the cell enzyme activities,while the physiological characteristics profiles of the isolates seemed to be related to the geographical distribution of their host.Among the actinobacteria isolates from desert soil crusts,Geodermatophilaceae were the predominant group.Combined the 16S rRNA gene information and the phenotypic data,these newly isolated Geodermatophilus members can be classified as 33 "species clusters".The physiological characteristics profiles of these Geodermatophilus members from different types of crusts or bare sand sample presented micro-ecological environment specific.In total of 329 strains identified to affiliate to 62 genera of 40 families in 5 phyla were purified from the fresh water ecosystem involved in cyanoHABs.Most of them were rarely found in other environments,and 9 novel microbial taxa were identified.The ecological roles of these strains and the relationship between the strains and their related organisms were in depth study.The fermentation broths from 19.7%of theses strains exhibited activity in at least one of the six antibiotic screening models.These studies indicated that the diverse bacteria and actinobacteria from the specific extreme enviroments may represent a goup of major potential functional microorganisms.