The Temporal And Spatial Evolution Of Bacteria And The Profile Distribution Of Bacteria Associated With Carbon Fixing In Typical Farmland

The core contents of microbial biogeography are the evolvement rules of soil microbes in horizontal space,vertical section and time series,which not only affect soil ecosystem function dramatically,but also driven by various factors both anthropogenic and natural.Due to the tiny individual,large quantity,wide varieties of soil microbes and high variability in soil micro-environments,the researches in space-time evolution aspects are relatively feeble.Besides,the previous studies hadn't concluded the same results,so it is urgent to develop further researches in soil microbial biogeography.We collected different reclamation-year farmland soil in the east of Zhejiang and the paddy soil in the south of anhui,and test the former one with Illumina MiSeq to discuss the soil bacterial community diversity,temporal and spatial erosion process in different reclamation years.The latter samples in anhhui were analysed with qPCR and PCR-RFLP,the physical and chemical properties are combined with microbial community structure and diversity of different profiles to reveal the driving environment factors of soil microbial diversity.Specific results were indicated as follows:Determination of physicochemical properties of 51 soil samples in the land sea interface farmland with different reclamation ages in Cixi City,Zhejiang province were determined,soil organic matter,total nitrogen,alkaline nitrogen and soil pH showed a significant correlation with soil reclamation ages,the contents of organic matter(R2=0.7415),total nitrogen(R2=0.7758)and alkaline nitrogen(R2=0.6932)increasing in the following reclamation ages,the soil pH(R2=0.6277)tend to be neutral in the following reclamation ages.A total of 16.8×106 high quality sequences were obtained by Illumina MiSeq sequencing,and the average length is 466bp.A total of 10874 OTU were obtained with the cutoff value of 0.03.Statistical analysis results showed that the bacterial diversity of reclaimed soil was significantly higher than that of nonreclaimed soil,but the bacterial community diversity index and abundance index have no significant correlation with the reclamation years in the reclaimed soil.Beta diversity statistics showed that the reclamation is a key factor affecting the soil bacterial community structure,the reclamation time has a little influence on the distribution of soil bacterial communities,and the soil bacterial communities which have the conjoint reclamation years were more similar to each other.A phylogenetic analysis showed that Proteobacteria,Acidobacteria,Bacteroidetes,Firmicutes,Actinobacteria,Chloroflexi,Nitrospirae,Gemmatimonadetes,Thaumarchaeota,Verrucomicrobia were the dominant microorganisms in soil,and found that the relative abundance of Chloroflexi,Nitrospirae,Ktedonobacteria,Thermomicrobia,Roseiflexus and Nitrospira can be used as an index to measure the ages of soil reclamation.The correlation between the soil bacteria community composition and environmental factors showed that soil electrical conductivity,pH,organic matter,total nitrogen,available potassium is an important biochemical index on soil bacterial communities,and the similarity between the sample bacterial community composition were gradually decreased with the increase of geographic distances.The cbbM,cbbL and coxL genotypes of microbial quantity and community diversity analysis using qPCR and PCR-RFLP technology were detected in three soil profile layers sampling at five area in Xuancheng,Anhui Province.The results of fluorescence quantitative showed that the cbbM genotype of microorganisms in each soil sample copy were ranged from 0.62×108 copies·g-1 dry soil to 9.80×108 copies·g-1 dry soil,and the number decreased at first and then increased with the increase of the soil depth,the distribution of Thiobacillus,Sulfuritalea and Rhodopseudomonas on the soil caused that.The results of PCR-RFLP showed that the genetic diversity of cbbM bacteria increased in the beginning and then decreased gradually with the increase of soil depth.The?-proteobacteria and ?/?-proteobacteria clone libraries were two dominant groups.Thiobacillus,Sulfuritalea,Rhodopseudomonas,Magnetospirillum were the dominant bacterial genus.The fluorescence quantitative results of cbbL gene showed that the number of cbbL green-like genotypes ranged from 0.97×107 to 2.10×107 copies·g-1 dry soil.The number of cbbL red-like gene were ranged from 5.84×109 to 10.50×109 copies·g-1 dry soil,which is higher than cbbLG by two orders of magnitude.What's more,the two genes were all decreased with the increase of soil depth.The results of PCR-RFLP showed that the diversity of cbbL green-like decreased with the decline of soil profile,but the diversity of red-like had no similar rule.The results of beta diversity showed that soil layer is the main factor affecting the distribution of cbbL green-like genotype microorganisms,soil types and vegetation have a certain impact on the cbbL green-like diversity.?-proteobacteria??/?-proteobacteria??/?-proteobacteria were the main microbial groups,Sideroxydans lithotrophicus was the main bacteria genus of the cbbL green-like genotype.Rubrivivax,Methulibium,Rhizobium,Alcaligenes,Bradyrhizobium and Burkhllderia were the dominant groups of cbbL red-like genotypes microorganisms.Quantitative real-time PCR revealed that the number of coxL genes in different layers in the soil ranged from 0.42×108 to 5.79×108 copies·g-1 dry soil and decreased with the decline of soil profile at the begining but increased later.Besides,Deinococcus-Thermus,?-proteobacteria and ?-proteobacteria dominated in different layers of soil profile.The results of PCR-RFLP showed the significant differences of coxL genotype microorganisms in different samples.The analysis of beta diversity showed that the soil layer and soil type are the main factors affecting the distribution of coxL genotype microbial,and the CO oxidizing bacteria community have a high similarity in plow sole and the tillage layer,while a low similarity of percogenic layer with other layers was found in our researches.Phylogenetic analysis revealed that ?-proteobacteria,?/?-proteobacteria,?-proteobacteria,Bacteroidetes,Deinococcus-Thermus,Actinobacteria cluster 1 and Actinobacteria cluster 2 dominated in coxL genotypic microbial groups,and a-proteobacteria was the absolute dominant groups.On genus level,Bradyrhizobium(6.6%-48.1%)was the absolute dominant bacteria genera.