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Accueil du site → Master → Brésil → 2016 → Impacto da umidade do solo sobre a estrutura das comunidades bacterianas e sobre as atividades enzimáticas em solos da Caatinga e da Mata Atlântica

Universidade de Sao Paulo (2016)

Impacto da umidade do solo sobre a estrutura das comunidades bacterianas e sobre as atividades enzimáticas em solos da Caatinga e da Mata Atlântica

Bononi, Laura

Titre : Impacto da umidade do solo sobre a estrutura das comunidades bacterianas e sobre as atividades enzimáticas em solos da Caatinga e da Mata Atlântica

Impact of the soil humidity on structure of the bacterial communities and on the enzymatic activities in soils of the Caatinga and Atlantic Forest

Auteur : Bononi, Laura

Université de soutenance : Universidade de Sao Paulo

Grade : Mestra em Ciencias 2016

Résumé
The microbial communities regulate the nutrient cycling in the soil. The impact of climate change on could alter the structure and function and cause an imbalance of nutrients in the environment. The main aim of this work was to study the impact of the soil humidity on diversity and enzymatic activities of bacterial communities in microcosms compounds soils of the Biosphere biomes of Caatinga and Atlantic Forest. Soil samples were collected in the following Brazilian states : Bahia, Pernambuco and Sao Paulo totaling four collection points, with a point in each state and two points in São Paulo. The soils samples of the two Biomes, were incubated in microcosms, with three humidity cycles (60% - 30% relative humidity) and for each humidity cycle, was constructed a 16S rRNA gene library. In the analyzes of alpha diversity, the PD indices were calculated (based on phylogenetic diversity branches of the phylogenetic tree) and Shannon and to test the beta diversity we used the Bray-Curts index (similarity index based on the dominant groups) and the distance UniFrac. Simultaneously, each soil sample of each treatment was analyzed for the following enzymatic activities : acid and alkaline phosphatase, arylsulfatase, dehydrogenase, cellulase, amylase, urease and phytase. The results herein obtained showed that the Phyla Acidobacteria, Proteobacteria and Chloroflexi were more abundant in the soils at Atlantic Forest, and Actinobacteria, Proteobacteria, Chloroflexi and Acidobacteria in the soils of Caatinga, considering the studied trait of the adverse effect of water stress. The most prevalent classes in the Atlantic Forest were Acidobacteria, Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria. While for the Caatinga, the prevalent classes were Ktedonobacteria, Actinobacteria-6 and Betaproteobacteria. In regard to the hydric stress on the enzymatic activities, the data showed significant effects for all sampling soils, except for the enzyme phytase. By correlations between OTUs and enzymes it was observed that specific groups were positively correlated with the activity of the enzymes and carbon and total nitrogen in the studied soils. These results indicate that humidity cycle affects the taxonomic distribution of bacterial communities and the enzymatic functions.

Mots Clés  : Alterações climáticas Atividade enzimática Estresse hídrico Semiárido Climate Change Enzymatic activity Semiarid Water stress

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