Isolation Of Rhizosphere Actinomycetes From Medicinal Plants In Yili River Valley Of Xinjiang And Multiphase Classification Of Seven Species Of Rare Actiomycetes

Rhizosphere generally refers to a small region which is closely surround with the root, it is 1-4mm apart from the root surface or a even smaller area, rhizosphere and its surrounding soil constitute a special micro ecological environment, biological and physical properties of the region generally are affected by plant roots. Plant rhizosphere microbial community structure characteristics showed significant difference from soil microbial community structure in neighboring environment, the rhizosphere region is an ideal place to discover actinomycetes resources.Ili River Valley is located in the northwest Xinjiang Uygur Autonomous Region, belongs to xinjiang desert region. The landform of Ili River Valley is complicated, surrounded by mountains on three sides, forming a "U" shaped valley. Ili River Valley is located in semi-arid climate zone. And also, because of its special topography, rainfall is relatively abundant, forming a "wet island" in the desert. Its superior geographical environment provides good conditions for the development of vegetation, and gives birth to a rich variety of medicinal plant species.80 medicinal plant rhizosphere soil samples were collected from Xinjiang Ili River Valley of northwestern China in this study. Actinobacterium selective medium were used to separate actinomycetes, and 1267 strains were obtained. After comparing with morphological characteristics,384 representative strains were selected to analyze their 16S rRNA gene sequences. The results showed that the strains affiliated to 71 genera of 30 families in 3 phyla:Actinobacteria, Proteobacteria and Firmicutes.5 strains among them may represent 5 new taxa.3 rare actinobacterial isolates were identified by using polyphasic approach. According to the comparison between 3 isolates and its type strains in cultural, morphological, physiological, biochemical characteristics and molecular systematic, we identified their taxonomic status. Identifiing 4 strains by using polyphasic approach were supplemented.Whole-cell hydrolysates of strain CPCC 204279T contained galactose and arabinose as diagnostic sugars and meso-diaminopimelic acid as the diamino acid. The predominant menaquinone was MK-9(H4). The phospholipids consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannosides. The major fatty acids were iso-C16:0, iso-C16:02-OH, C16:1ω9C, iso-C16:1 and C16:0. The genomic DNA G+C content was 73.2 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CPCC 204279T should be placed in the family Pseudonocardiaceae, in which the strain formed a distinct lineage next to the genus Actinophytocola. The combination of phylogenetic analysis and phenotypic characteristics supported the conclusion that strain CPCC 204279T represents a novel species of a new genus in the family Pseudonocardiaceae, for which the name Herbihabitans rhizosphaerae gen. nov., sp. nov. is proposed.Strain CPCC 204380T contained glucose, xylose, mannose and ribose as diagnostic sugars in whole-cell hydrolysates. The predominant menaquinone was MK-10. The phospholipids consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannosides. The major fatty acids were iso-C15:0、iso-C16:0 and C17:1 ω9C. The genomic DNA G+C content was 64.9 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CPCC 204380T should be placed in the family Micromonosporaceae, in which the strain formed a distinct lineage next to the genera Rhizocola. The combination of phylogenetic analysis and phenotypic characteristics supported the conclusion that strain CPCC 204380T represents a novel species of a new genus in the family Micromonosporaceae.The 16S rRNA gene sequences comparisons yielded 93.9% to 97.8% similarities of strain CPCC 203993Twith members of the genus Microlunatus. In the phylogenetic tree based on 16S rRNA gene sequences, strain CPCC 203993T was included in the clade of the genus Microlunatus next to Microlunatus parietis DSM 22083T While the DNA-DNA hybridization value (31.5±1.8)% between strain CPCC 203993T and Microlunatus parietis DSM 22083T was far below 70%. Chemotaxonomically, the strain contained LL-2,6-diaminopimelic acid as the diagnostic diamino acid, MK-9(H4) in the menaquinone system, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, three unidentified glycolipids, and one unidentified phospholipid in the polar lipids extracts, and anteiso-C15:0,iso-C15:0 and iso-C16:0 as the major cellular fatty acids, without mycolic acids. The genomic G+C content was 64.04 mol%. The aforecited polyphasic taxonomy evidences clearly warranted the creation of a novel species in the genus Microlunatus, for which Microlunatus nigridraconis sp. nov. is proposed.Strain CPCC 203552T and strain CPCC 203553T were supplemented with taxonomic indicators in their cultural characteristics, morphological characteristics, physiological characteristics and genomic G+C content. The combination of phylogenetic analysis and phenotypic characteristics supported the conclusion that strain CPCC 203552T and strain CPCC 203553T represents a novel species in the genus Angustibacter.Strain CPCC 203554T and strain CPCC 203555T were supplemented with taxonomic indicators in main polar lipids, genomic G+C content, and DNA-DNA hybridization between strain CPCC 203554T and strain CPCC 203555T. The combination of phylogenetic analysis and phenotypic characteristics supported the conclusion that strain CPCC 203554T and strain CPCC 203555T represents two novel species in the genus Modestobacter.In this study, we preliminarily evaluated the diversity of medicinal plant rhizosphere actinobacterium in Ili River Valley. Significant information about the community structure and species diversity was gained. The study provided the basis for in-depth understanding of interactions between rhizosphere actinobacterium and plant, enriched the medicinal plant rhizosphere actinobacterium resources and data to some extent. The research also provide basic data for the development, utilization and protection of plant rhizosphere actinobacterium resources.