| Soil biological activity is essential for the sustainable development of agriculture,soil microbes drive many basic soil cycle,including soil material cycle,energy conversion,degradation of pollutants and other ecosystem services.Microbial community structure change is an important index to judge the change of soil quality.In recent years,more and more attention has been paid to the influence of organic agriculture on soil microbial community and its function.Soil microbial changes of organic planting patterns,and these contact and soil microbial community changes and soil quality,soil nutrient,soil borne diseases of ecological service function is a key issue in the present study.Based on the representative organic production base,the response process of organic planting pattern and the consistency of changes of soil microorganism,found as "healthy soil microbial characteristics" with organic farming soil,mining of some organic farming methods have the functional microbial positive response has important scientific value.In addition,the process of bacterial community and functional succession in different developmental stages of crops,and the response process of specific functional microorganisms to organic fertilizer,is an important basis for the selection and application of functional microorganisms.In this paper,6 groups of organic farms and their corresponding conventional farms were selected to study the microbial communities in the central provinces of central China(4 provinces).Studies on the microbial succession of rice at different rice growth stages and fertilizer treatments in Jintan,Jiangsu.The function,structure and genetic diversity of microbial community were studied by using soil enzyme activity,Biolog micro plate,phospholipid fatty acid(PLFA)and high throughput sequencing Miseq PE300.Through correlation analysis,difference analysis(LefSe),ecological network analysis and bacterial functional annotation analysis(PICRUSt)and so on,the changes,differences,relationships and functions of microorganisms were studied.In addition,we also studied the isolation and purification of the significant changes in the results of the predatory bacteria(bacteria),and explore the potential functional microorganisms.Microbial community stuctures to organic farming:Soil microorganisms play a crucial role in the biogeochemical cycling of nutrient elements and maintaining soil health.Farming practices have been proven to influence the composition of soil bacterial communities.However,bacterial community features in different crop and soil types under organic management have rarely been investigated.The effect of crop types(rice,tea and vegetable)and management strategies(organic and conventional)on the composition and diversity of bacterial communities were investigated in 36 soils sampled along the middle and lower reaches of the Yangtze River.Compared with conventional farming,organic farming significantly increased soil nutrients,soil enzyme activities,and bacterial richness and diversity.A Venn diagram and principal component analysis revealed that the soils with 3 different crops under organic farming have more number and percent of shared OTUs(operational taxonomic units),and shared a highly similar microbial community structure.Under organic farming,several predominant guilds and major bacterial lineages(Rhizobiales,Thiotrichaceae,Micromonosporaceae,Desulfurellaceae and Myxococcales)contributing to nutrient(C,N,S and P)cycling were enriched,whereas the relative abundances of acid and alkali resistant microorganisms(Acidobacteriaceae and Sporolactobacillaceae)were increased under conventional fanning practices.More interesting,the tea soils that experienced less human intervention were more responsive to organic farming practices than the rice or vegetable soils.Our results indicated that farm management practices had a significant effect on the bacterial community structure compared with various crop types.Organic farming promoted soil bacterial diversity and the uniformity of the bacterial community structure.Predation commonly been viewed as a key factor in regulating community structure or function.Although predation has been extensively explored in animals and microbial eukaryotes,predation by bacteria in agriculture land is less well understood.The aim of this study was to explore the structure of the predatory bacterial community and their potential effect on other bacteria.Three crop type soils were selected,and result showed that predatory bacteria accounting for a major proportion in the soil bacterial.Soil pH is the most important soil properties that positive correlated more than half of the predatory bacteria(P<0.05,include Myxococcales).Although some predator were not detected in all soil types or samples.But Myxococcales have a high abundance and widespread distribution in all soil samples.Moreover,Myxcocaccales(included mostly family of it)distribution is relatively uniform in the three kinds of soils.More interesting,Myxococcales not only significantly positive correlation with other 8 predatory bacteria,but it is also the only one predator significantly with bacteria community diversity index(Shannon and ACE).Network analysis showed that predatory bacteria(especially the genus of Myxococcales)have co-occurrence with other nutrition-related bacteria.In organic condition the abundance of Myxococcales were significant increase.And considering that Myxococcales is more versatile in predation strategy,higher 'bacterial IQ' and broader spectrum of prey than other predators.We conclude that Myxococcales is the most widespread distribution,important and active predator and tightly correlated with other bacteria and community diversity in 3 different soils we studied.But there also need more directly evidence to illustrate the fact that Myxococcales shift the bacteria community structure.The succession of soil microbial community and microbial function in rice key growth stages are often overlooked in microbial ecology.In this article we investigate succession of soil bacterial for four fertilizers treatment(control,NPK,NPK + manure and NPK + straw)and 3 crucial rice growth stages(tillering,heading,and ripening)paddy soil in 10 years rice-wheat cropping system.We found that rice growth-stage related dynamics of the soil chemical properties,bacterial community and bacterial functions structure.The bacterial community composition of control treatment were quite different to the other NPK fertilizers,but plus pig manure in NPK could modify bacterial community in heading and ripening stages.In addition,the bacterial community of tillering were obviously distinguish from heading and ripening stages.Soil bacterial community network were complex in the heading stage and maintained relatively stable structure in heading and ripening stages.But functional networks were stable in early and middle stage,and formed an intimate yet complicated co-occurrence network in ripening stage.These results suggest there has obvious succession of soil bacterial and bacteria function in rice key growth stages,but the succession of paddy soil bacterial community network structure were not completely consistent with the changes in function network.Based on the above research,this paper takes the organic agriculture model as the starting point to explore the beneficial microbial groups.The organic model promoted the consistent change of soil bacteria,such as the more common species(OTU),the similarity of bacterial community structure and the change of microbial community abundance.We found that the abundance of many nutrition related bacteria increased in organic mode.The study of predatory bacteria was based on organic and conventional samples,and the results showed that the predatory bacteria had an important position in agricultural soils.In addition,the predatory bacteria are the most widely distributed and the most closely related to the bacterial community structure and ecological network.Taking into account the significant increase of the bacteria in the organic model.We isolated and purified a number of bacteria and studied their ability to antagonize pathogenic fungi.In addition to fertilizer treatment,we also studied the effect of rice development period on the structure and function of bacterial community.However,the process of bacterial succession is not completely synchronized with the functional succession of bacteria. |
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