Community structure of soybean plant growth-promoting rhizobacteriain the black soil region of Northeast China

As the black soil area of Northeast China is major soybean producing areas, it is important for the sustainable development of agriculture to study the soybean plant growth-promoting rhizobacteria (PGPR). For explaining the community structure of soybean PGPR in the black soil region of Northeast China, we chose four sample stations including Ewenki Autonomous Banner in Inner Mongolia Autonomous Region, Hailun City in Heilongjiang Province, Keshan County in Heilongjiang Province and Hongxinglong Farms in Heilongjiang Province, analyzed community composition of nitrogen-fixing bacteria, phosphate-dissolving bacteria, phosphate-solubilizing bacteria and silicate bacteria in soybean rhizosphere, and interpreted correspondence relationship between PGPR strains and areas. The results showed a large number of PGPR in soybean rhizosphere. The quantity of nitrogen-fixing bacteria reached to 104 cfu·g^?1, these of phosphate-dissolving bacteria and phosphate-solubilizing bacteria reached to 105 cfu·g^?1, and that of silicate bacteria reached to 103 cfu·g^?1. Species groups of nitrogen-fixing bacteria, phosphate-dissolving bacteria, phosphate-solubilizing bacteria and silicate bacteria in soybean rhizosphere consisted of 5, 6, 7 and 4 species respectively. Shannon-Weiner biodiversity indices of nitrogen-fixing bacteria, phosphate-dissolving bacteria, phosphate-solubilizing bacteria and silicate bacteria were higher in soybean rhizosphere, which were in ranges of 0.94~1.60, 0.83~1.52, 1.07~1.67 and 0.52~0.96.Biodiversity indices of PGPR were more than 2 in sampling stations. Analysis on correspondence relationship between PGPR strains and areas indicated typical PGPR of different sampling stations. Nitrogen-fixing bacteria LLN8 (Azotobacter beijerinckia indica), phosphate-dissolving bacteria DHS13 (Micrococcus), phosphate-dissolving bacteria DHS19 (Pseudomonas), nitrogen-fixing bacteria LLN1 (A. chrooco-ccum) and phosphate-dissolving bacteria DHS5 (Azotobacter) were typical PGPR strains for Ewenki Autonomous Banner in Inner Mongolia Autonomous Region, Hailun City in Heilongjiang Province, Keshan County in Heilongjiang Province, Hongxinglong Farms in Heilongjiang Province, respectively. The paper cleared that some strains including LLN2 (A. azomonas), LLN6 (B. mucilaginosus), DHS9 (Arthrobacter), DHSO2 (Pseudomonas), DHSO14 (Erwinia), DHSO17 (Corynebacterium) and LSJ21 (Bacillus) were widespread in the black soil area of Northeast China through correspondence analysis, the strains could serve as an important foundation of special compound bio-fertilizer production.