Bacterial Diversity in the Rhizosphere of Halophyte Phragmites communis at the Western Coastal Mudflats of Korea

This study investigated the population densities and diversity of heterotrophic bacteria, and therhizosphere-to-soil ratios (R/S) in the rhizosphere soil of halophyte Phragmites communis at the western coastalmudflats of Korea. The population densities of aerobic heterotrophic bacteria on the rhizosphere soil of P. communiswere in the range of 3.3 ± 0.9 × 107～1.2 ± 0.5 × 108 cfu g-1 dry weight (d. wt.). Population densities ofamylolytic bacteria ranged from 1.1 ± 0.2 × 106 to 3.0 ± 1.2 × 106 cfu g-1 d. wt., while those of cellulolytic bacteriaand proteolytic bacteria ranged from 5.6 ± 2.3 × 106 to 1.5 ± 0.3 × 107 cfu g-1 d. wt. and from 1.4 ± 0.3 × 106to 3.5 ± 2.3 × 107 cfu g-1 d. wt., respectively. The R/S ratios ranged from 2.26 to 6.89. Genetic (16S DNA) analysisof fifty-one isolates from the roots of P. communis suggested that the dominant species were closely relatedto the γ-proteobacteria group (18 clones) and the α-proteobacteria group (14 clones). We found that halophytespecies and mudflat environment both affected the rhizosphere bacterial communities.