Studies On Phylogenetic Diversity Of Unculturable Bacterias From Angelica Sinensis Rhizosphere Under Different Residues

Soil microbes can not only sustain the balance of decomposition and composition of soil organic matters, but also improve soil fertility by mineralizing the organic matters. Therefore, keeping the normal constitution and distribution of microbial populations in soil can assure the stability and development of agricultural ecosystem. In this study, PCR-DGGE technique was used to study the angelica rhizosphere bacterial diversity under different residues. The results are as follows:1. The angelica seedlings showed a significant difference in growth and development under different residues. Compared with the seedlings grown under wild soil, the seedlings under Huangqi residue are vigorous as well, even their roots developed much better. However, the seedlings under potato and angelica residues are significant weaker, indicating that Huangqi residue is a kind of adapted seedbed soil for angelica, which can replace wild soil.2. The soil fertility showed a significant difference by the end of seedling stage under different residues. The margin nutrients in wild soil are richer probably because of good base, but they are poor in Huangqi residue with better growth, indicating that organic manure should be applied when the residue is used to culture angelica seedlings. The results also showed that the soil acidity and alkalinity varies with residues, of which both potato and angelica residues showed strong alkalinity (pH>8.8), and the wild especially Huangqi residue showed weaker alkalinity, which is propitious to angelica seedling, All these results provided a good evidence for angelica seedling difference under different residues.3. A PCR-DGGE method system was firstly established in this study. The genomic DNA of bacterial community was e directly xtracted from the soils. After purification, the 16Sr DNA genes (V3 region) was amplified by the primers (F341GC and R518) which were specific for most bacteria and archaebacteria and then the PCR products about 200bp long were separated in 10% polyacrylamide gels with a denaturant (where 100% denaturant contains the 7M urea and 40% formamide) gradient from 30% to 60%. The information of bacterial diversity in these soils was showed by the DGGE profiles analysis.4. The unculturable bacterial diversity of the soils in different residues was studied by PCR-DGGE technique. The results showed that the unculturable bacterial genetic diversity had a significant difference in various soils. Similar analysis of the 16S rDNA-V3 fragments showd that the diversity of angelica rhizosphere microbe population is more obvious in the beginning of seedling and then it gradually came to the same later.5. 16S rDNA-V3 fragments from 21 individual DGGE bands were sequenced and submitted to NCBI (EU555004-EU555024). The detailed corresponding bacteria were found based on BLAST alignment. Proteobacteria, Bacteroidetes, Cyanobacteria, Chloroflexi, Chlorobi and Actinobacteria make up the majority of the dominant bacteria in angelica rhizosphere under different residues, which is probably important for the growth and development of angelica seedlings.