Community Structure And Diversity Of Bacteria In Typical Field Soil Of Tanggu

The soil of Tanggu area in Tianjin has a high degree of soil salinization, which is saline soil. At present, the researches on community structure and diversity of bacteria in saline soil are very rare. We will analyze the community structure and diversity of bacteria by PCR-RFLP. The research will play a significant role in the use of land reasonably.The saline soil of Xincheng Town (S1, S2, S3, S4 and S5) and Sidaoqiao (S6, S7 and S8)in Tanggu was used as the test material. The three land use patterns were farmland (S1, S2, S6, S7 and S8), vegetable plot (S3 and S4) and fruit orchard (S5).Total genomic DNAs of bacteria were extracted directly from the soil. After purification, the 16S rDNAs were amplified from the total genomic DNA by PCR with the bacterial universal primers 27F/1492R. After connecting the amplifier into pMD19-T vector and transforming into E.coli JM109, the positive clone was screened by white bacterial colony, and then the clone library was constructed. The 16S rDNAs were amplified from the inserted partial sequence by colony PCR with the universal primer M13 of pMD19-T vector. After purification, the colony amplifiers were digested by HhaⅠand RsaⅠ. The cleavage products will electrophsised on 2% agarose gels and then the RFLP patterns were obtained by statistic analysis of gel. The diversity indices were calculated according to the RFLP patterns. Some typical clones were sequenced. The species messages were obtained from NCBI by 16S rDNA sequence BLAST. Phylogenetic analysis was done based on partial 16S rDNA sequencing of the typical clones. Some results were obtained as following:1. Total OTUs of eight soil samples are 93 (S1), 165 (S2), 115 (S3), 158 (S4), 163 (S5), 183 (S6), 156 (S7) and 171 (S8), respectively. The ratio of single clones in every clone library is very high, with the order of S6>S2>S4>S8>S7>S5>S3>S1. A same preponderant RFLP type exists between S1 and S3, whose ratio were 33.70% and 19.50% respectively, while no dominant type exists in other samples.2. Theαdiversity indices indicated that there was a pronounced difference among the eight soil samples. Four diversity indices were highest in S6 while lowest in S1. H′and d_Ma changed in different soils with an order of S6>S8>S2>S5>S4>S7>S3>S1. Ds and E were the same trends and represented an identical order S6>S8>S2> S7>S4= S5>S3>S1 and S6>S8>S2> S7>S4>S5>S3>S1. The rescaled distance matrix tree indicated that there was a high community similarity in S4 and S7, while there was a low community similarity between S1, S3 and other samples.3. Phylogenetic tree of 16S rDNA sequences showed that the sequenced clones fell into nine major lineages within the domain bacteria. Among them, members of the Acidobacteria were dominant group, followed by Proteobacteria, Firmicutes and Actinobacteria. Nitrospira, Chloroflexi, Gemmatimonadetes, Planctomycetacia and some uncultured batteries were less well represented.These results demonstrated that the diversity of bacteria in coastal saline soil was extensive and the community similarity was different during eight samples.