Microbial Characteristics Of Salvia Miltiorrhiza Bge Continuous Cropping Soil In Zhongjiang, Sichuan

Soil samples collected from Salvia GMP Demonstration Planting Base (in Shiquan Country Zhongjiang County Sichuan Province), including sick Salvia rhizosphere (HD1) and sick Salvia non-rhizosphere soil (HD2), rhizospheric soil of normal growth of Salvia (CK1) and its non-rhizospheric soil (CK2) were used to analyze soil microbial flora by pour plate counting method, and then 46 bacterial strains were isolated and purified. BOXAIR-PCR,16S rDNA PCR-RFLP and 16S rRNA gene sequence analysis was performed to reveal the genetic diversity of the tested strains, and to identify their phylogeny and classification. PCR-DGGE was used to analyze the soil microbial diversity by using soil DNA sample, and expected to reveal the obstacle factors for Salvia continuous cropping soil. Soil microbial biomass and activity were also measured. The results were as following:(1) The number of microorganism in rhizosphere and non-rhizosphere soil was quite different in Salvia planting soil, and the amount of bacteria was the highest, then actinomycetes was the second, and that of fungi was the lowest.(2) 46 bacterial strains were isolated from Salvia planting soil, of which, the dominant bacteria was G+ with a total of 25 strains, meanwhile, a total of 21 strains were G-. Bacillus was the predominant microflora in G+ bacteria(3) Analysis of soil microbial biomass showed that, soil microbial carbon and nitrogen of control rhizosphere soil (CK1) was higher than,32.4% and 64% respectively, that of the sick Salvia rhizosphere soil (HD1); however, in the non-rhizospheric soil (CK2 and HD2), the difference was not very clear.(4) The results of soil enzyme activity analysis showed that, the enzyme activity in the sick Salvia rhizosphere soil (HD1) was lower than that in the control rhizosphere soil (CK1), and ALP was lower than 53.3%, URE was lower than 38.5%, CAT was lower than 11.1%, respectively, which indicated that enzyme activity in sick Salvia soil has greatly decreased.(5) Genetic diversity analysis showed that they were very diverse among 46 bacteria isolated from Salvia planting soil. All the strains were divided into seven genetic groups at the level of 71% similarity by BOXAIR-PCR and at the level of 79% similarity by 16S rDNA PCR-RFLP analysis.(6)The phylogeny of 12 representative strains was determined according to 16S rRNA gene sequencing, the results showd that these strains belong to genus Bacillus, Pseudomonas, Brevibacterium, Agrobacterium and Lysinibacillus, respectively. (7) Furthermore, PCR-DGGE was used to reveal the microbial diversity based on the total soil DNA, and some specefic DGGE bands were picked and cloned to do sequence analysis and the phylogenic tree were obtained. The results suggested that, excepet for some strains distruted in genus Chaetomium(homology 98%) and genus Phoma(homology 99%), many strains located in the branch of uncultured bacteria and fungi in continuous cropping Salvia soil.