목차

Content
1.General introduction 1
1.1. Plant growth-promoting rhizobacteria 1
1.2. Salt stress 3
1.3. Amelioration of salt stress in plants by PGPR strains 3
1.4. Aim of this study 7
2. Comparative Study of Rhizobacterial Communities in Pepper Greenhouses under Repeated Cropping System and Paddy-Upland Rotational System 9
2.1. Introduction 9
2.2. Materials and Methods 13
2.2.1. Soil sampling and characterization 13
2.2.2. Isolation of bacteria 15
2.2.3. Partial identification of bacterial isolates using sequence analysis of 16S rRNA genes 15
2.2.4. PGP characteristics 16
2.2.5. Genomic DNA extraction from the soil 17
2.2.6. Tag-encoded amplicon pyrosequencing 18
2.2.7. Data and statistical analyses 21
2.3. Results 23
2.3.1. Soil Characterization 23
2.3.2. Isolation and partial identification of rhizobacteria characteristics 25
2.3.3. PGP traits in the bacterial isolates 29
2.3.4. Pyrosequencing data analysis 32
2.3.5. Distribution of bacterial taxa 35
2.3.6. Correlation analysis between soil properties and the bacterial community structure associated with soils of different cropping systems 39
2.4. Discussion 42
3. Application on Pepper of Plant Growth-Promoting Rhizobacteria for Alleviating Salt Stress 51
3.1. Introduction 51
3.2. Materials and Methods 54
3.2.1. Plant material and growth condition 54
3.2.2. PGPR strains, bacterial inoculation, and salt stress treatment 54
3.2.3. Measurement of plant growth parameters and chlorophyll and water contents in leaf tissue 55
3.2.4. Antioxidant enzyme assays 56
3.2.5. Determination of proline and total soluble sugar (TSS) contents 57
3.2.6. Statistical analysis 58
3.3. Results 59
3.3.1. Characteristics of the three PGPR strains 59
3.3.2. Effect of PGPR isolates on pepper growth 62
3.3.3. Leaf chlorophyll content and leaf related water content (LRWC) under normal and saline conditions 65
3.3.4. Antioxidant enzyme activities in pepper plants inoculated with PGPR 67
3.3.5. Accumulation of proline and total soluble sugar in pepper leaves 69
3.4. Discussion 71
4. Bacillus salini sp. nov., a Novel Strain Isolated from the Pepper Rhizosphere under Salt Stress Condition 75
4.1. Introduction 75
4.2. Materials and Methods 77
4.2.1. Phylogenetic analysis 77
4.2.1.1. Sequencing of 16S rRNA gene from isolate 77
4.2.1.2. Partial identification and phylogenetic analysis of 16S rRNA gene sequences 79
4.2.2. Identification of phenotypic characteristics 80
4.2.3. Identification of physiological and biochemical
characteristics 82
4.2.4. Analysis of G+C contents 83
4.2.5. Extraction and analysis of isoprenoid quinones 83
4.2.6. Extraction and analysis of cellular fatty acids 84
4.2.7. Extraction and identification polar lipid 85
4.3. Results and discussion 86
4.3.1. Phylogenetic analysis 86
4.3.2. Phenotypic characteristics 89
4.3.3. Physiological and biochemical characteristics 92
4.3.4. Major isoprenoid quinone and composition of cellular polar lipids 93
4.3.5. Isoprenoid quinone and cellular fatty acid profiles 97
4.4. Taxonomic conclusion 99
4.5. Summary 99
5. Summary 101
6. References 105
국문 초록 126