Efeito da disponibilidade de água na composição e função de comunidades microbianas presentes no solo do cerrado revelado por análises metagenômicas

Tese (doutorado)—Universidade de Brasília, Instituto de Biologia, Departamento de Biologia Celular, Pós-Graduação em Biologia Molecular, 2013.O Cerrado, bioma exclusivamente brasileiro, compreende alta heterogeneidade de vegetação e duas estações bem definidas durante o ano sendo estes invernos secos e verões chuvosos. Embora uma quantidade considerável de informação esteja disponível sobre a diversidade de fauna e flora presente no Cerrado, pouco se conhece sobre a composição, estrutura e funcionamento biológico das comunidades microbianas nas diferentes fitofisionomias nativas associados a este bioma. Nesse contexto, genes do rRNA (16S em procariotos e 18S em eucariotos) e posteriormente do DNA total (metagenoma) extraídos diretamente de solo a partir de quatro tipos de vegetação ontrastantes (cerrado denso, campo sujo, cerrado sensu stricto e mata de Galeria) durante as estações secas e chuvosas foram analisados por meio de pirosequenciamento. As análises comparativas das quatro fitofisionomias revelaram uma distinta distribuição de filos de Bactérias, Archaea e Fungos. De acordo com a riqueza de OTU estimada pelo índice de Chao1, a estação chuvosa apresentou maior riqueza de OTUs para as comunidades de bactérias e fungos. Em contraste, a estação seca demonstrou possuir maior riqueza de OTUs para a comunidade de archaea. Aparentemente, houve forte influência da umidade do solo com a composição da comunidade microbiana sugerindo que o teor gravimétrico de água nas amostras de solo pode ser considerado como um dos preditores de variabilidade dentro da diversidade microbiana presente em amostras de solo do bioma Cerrado. Além disso, análises dos dados metagenômicos revelaram aumento significativamente estatístico na abundância relativa de genes associados com o metabolismo e aquisição de ferro, elementos transponíveis, dormência e esporulação durante a estação seca. Em adição, genes relacionados ao metabolismo de DNA e gados à respiração tiveram sua abundância relativa enriquecida durante a estação chuvosa. Essas categorias funcionais geralmente podem estar associadas aos mecanismos de adaptação da comunidade microbiana a estresse hídrico. Em suma, estes resultados podem ajudar a construir conclusões mais compreensivas sobre a capacidade funcional das comunidades microbianas de solos nas estações seca e chuvosa. ______________________________________________________________________________ ABSTRACTThe Cerrado occurs primarily in Brazil. Its vegetation varies considerably in physiognomy and there are two well-marked and seasonal climates, one wet summer and one drought winter. Although a considerable amount of information is available regarding the fauna and flora diversity present in the Cerrado, little is known about the composition, structure and biological function of microbial communities in different native physiognomies associated to this biome. Using barcode pyrosequencing of the rRNA (16S/18S rRNA) genes and shotgun metagenomics analysis with DNA directly extracted from four contrasting physiognomies (cerrado denso, campo sujo, cerrado sensu stricto and mata de galeria) in the two different time points (drought and rain) were performed. Comparative analysis of the four type vegetation soil samples revealed a distinct distribution of bacterial, archaea and fungal phyla. According to the OTU richness estimated by Chao 1, the rain season is more species rich than drought season for bacterial and fungal communities; by contrast, the archaeal community showed is more species rich in the drought when compared with rainy season. Apparently, there was a strong influence of soil moisture on the composition of the microbial community suggesting that the gravimetric water content of soil samples can be considered as one of the predictors of variability within the microbial diversity present in soil samples from the Cerrado biome. Furthermore, analysis of metagenomic data revealed statistically significantly increased in relative abundance of genes associated with metabolism and iron acquisition, transposable elements, dormancy and sporulation during the dry season. In addition, genes related to metabolism of DNA and proteins as well as genes linked to respiration had enriched their relative abundance during the rainy season. These functional categories can generally be associated with the mechanisms of adaptation of the microbial community to water stress. Indeed, these results can help build more comprehensive conclusions about the functional capacity of microbial communities in soils of dry and rainy seasons

Exercise induction of gut microbiota modifications in obese, non-obese and hypertensive rats

Background: Obesity is a multifactor disease associated with cardiovascular disorders such as hypertension. Recently, gut microbiota was linked to obesity pathogenesisand shown to influence the host metabolism. Moreover, several factors such as host-genotype and life-style have been shown to modulate gut microbiota composition. Exercise is a well-known agent used for the treatment of numerous pathologies, such as obesity and hypertension; it has recently been demonstrated to shape gut microbiota consortia. Since exercise-altered microbiota could possibly improve the treatment of diseases related to dysfunctional microbiota, this study aimed to examine the effect of controlled exercise training on gut microbial composition in Obese rats (n = 3), non-obese Wistar rats (n = 3) and Spontaneously Hypertensive rats (n = 3). Pyrosequencing of 16S rRNA genes from fecal samples collected before and after exercise training was used for this purpose. Results: Exercise altered the composition and diversity of gut bacteria at genus level in all rat lineages. Allobaculum (Hypertensive rats), Pseudomonas and Lactobacillus (Obese rats) were shown to be enriched after exercise, while Streptococcus (Wistar rats), Aggregatibacter and Sutturella (Hypertensive rats) were more enhanced before exercise. A significant correlation was seen in the Clostridiaceae and Bacteroidaceae families and Oscillospira and Ruminococcus genera with blood lactate accumulation. Moreover, Wistar and Hypertensive rats were shown to share a similar microbiota composition, as opposed to Obese rats. Finally, Streptococcus alactolyticus, Bifidobacterium animalis, Ruminococcus gnavus, Aggregatibacter pneumotropica and Bifidobacterium pseudolongum were enriched in Obese rats. Conclusions: These data indicate that non-obese and hypertensive rats harbor a different gut microbiota from obese rats and that exercise training alters gut microbiota from an obese and hypertensive genotype background

Soil acidobacterial 16S rRNA gene sequences reveal subgroup level differences between savanna-like cerrado and atlantic forest brazilian biomes

16S rRNA sequences from the phylum Acidobacteria have been commonly reported from soil microbial communities, including those from the Brazilian Savanna (Cerrado) and the Atlantic Forest biomes, two biomes that present contrasting characteristics of soil and vegetation. Using 16S rRNA sequences, the present work aimed to study acidobacterial diversity and distribution in soils of Cerrado savanna and two Atlantic forest sites. PCA and phylogenetic reconstruction showed that the acidobacterial communities found in “Mata de galeria” forest soil samples from the Cerrado biome have a tendency to separate from the other Cerrado vegetation microbial communities in the direction of those found in the Atlantic Forest, which is correlated with a high abundance of Acidobacteria subgroup 2 (GP2). Environmental conditions seem to promote a negative correlation between GP2 and subgroup 1 (GP1) abundance. Also GP2 is negatively correlated to pH, but positively correlated to high Al3+ concentrations. The Cerrado soil showed the lowest Acidobacteria richness and diversity indexes of OTUs at the species and subgroups levels when compared to Atlantic Forest soils. These results suggest specificity of acidobacterial subgroups to soils of different biomes and are a starting point to understand their ecological roles, a topic that needs to be further explored

Diversity of soil fungal communities of Cerrado and its closely surrounding agriculture Welds

Cerrado is a savanna-like region that covers a large area of Brazil. Despite its biological importance, the Cerrado has been the focus of few microbial diversity studies. A molecular approach was chosen to characterize the soil fungal communities in four areas of the Cerrado biome: a native Cerrado, a riverbank forest, an area converted to a soybean plantation, and an area converted to pasture. Global diversity of fungal communities in each area was assessed through Ribosomal intergenic spacer analysis which revealed remarkable diVerences among the areas studied. Sequencing of approximately 200 clones containing 18S rDNA sequences from each library was performed and, according to the genetic distance between sequences, these were assigned to operational taxonomic units (OTUs). A total of 75, 85, 85, and 70 OTUs were identiWed for the native Cerrado, riverbank forest, pasture, and soybean plantation, respectively. Analysis of sequences using a similarity cutoV value of 1% showed that the number of OTUs for the native Cerrado area was reduced by 35%; for the soybean plantation, a reduction by more than 50% was observed, indicating a reduction in fungal biodiversity associated with anthropogenic activity. This is the Wrst studydemonstrating the anthropogenic impact on Cerrado soil fungal diversity

Microbial diversity in cerrado biome (neotropical savanna) soils

The Cerrado, the largest savanna region in South America, is located in central Brazil. Cerrado physiognomies, which range from savanna grasslands to forest formations, combined with the highly weathered, acidic clay Cerrado soils form a unique ecoregion. In this study, high-throughput sequencing of ribosomal RNA genes was combined with shotgun metagenomic analysis to explore the taxonomic composition and potential functions of soil microbial communities in four different vegetation physiognomies during both dry and rainy seasons. Our results showed that changes in bacterial, archaeal, and fungal community structures in cerrado denso, cerrado sensu stricto, campo sujo, and gallery forest soils strongly correlated with seasonal patterns of soil water uptake. The relative abundance AD3, WPS-2, Planctomycetes, Thermoprotei, and Glomeromycota typically decreased the rainy season, whereas the relative abundance of Proteobacteria and Ascomycota increased. In addition, analysis of shotgun metagenomic data revealed a significant increase in the relative abundance of genes associated with iron acquisition and metabolism, dormancy, and sporulation during the dry season, and an increase in the relative abundance of genes related to respiration and DNA and protein metabolism during the rainy season. These gene functional categories are associated with adaptation to water stress. Our results further the understanding of how tropical savanna soil microbial communities may be influenced by vegetation covering and temporal variations in soil moisture

Fatty Acids Consumption: The Role Metabolic Aspects Involved in Obesity and Its Associated Disorders

Obesity and its associated disorders, such as insulin resistance, dyslipidemia, metabolic inflammation, dysbiosis, and non-alcoholic hepatic steatosis, are involved in several molecular and inflammatory mechanisms that alter the metabolism. Food habit changes, such as the quality of fatty acids in the diet, are proposed to treat and prevent these disorders. Some studies demonstrated that saturated fatty acids (SFA) are considered detrimental for treating these disorders. A high fat diet rich in palmitic acid, a SFA, is associated with lower insulin sensitivity and it may also increase atherosclerosis parameters. On the other hand, a high intake of eicosapentaenoic (EPA) and docosahexaenoic (DHA) fatty acids may promote positive effects, especially on triglyceride levels and increased high-density lipoprotein (HDL) levels. Moreover, polyunsaturated fatty acids (PUFAs) and monounsaturated fatty acids (MUFAs) are effective at limiting the hepatic steatosis process through a series of biochemical events, such as reducing the markers of non-alcoholic hepatic steatosis, increasing the gene expression of lipid metabolism, decreasing lipogenic activity, and releasing adiponectin. This current review shows that the consumption of unsaturated fatty acids, MUFA, and PUFA, and especially EPA and DHA, which can be applied as food supplements, may promote effects on glucose and lipid metabolism, as well as on metabolic inflammation, gut microbiota, and hepatic metabolism

Impact of Iron Mining Activity on the Endophytic Fungal Community of <i>Aspilia grazielae</i>

Aspilia grazielae (J. U. Santos) is an endemic plant species in Morro do Urucum in the Pantanal wetland (Brazil). A. grazielae is used for the restoration of areas impacted by iron mining activities. This study evaluates the diversity (composition, value and abundance) of endophytic fungal communities, considering parts of the plant and soil condition. The leaves and roots of A. grazielae were collected from native vegetation areas (NVA) and recovery areas (RCA) in Morro do Urucum. Illumina sequencing technology was used to investigate variation in endophytic fungal biodiversity. The operational taxonomic units detected in NVA ranged from 183 to 263 (leaf) and 115 to 285 (root), while RCA samples ranged from 200 to 282 (leaf) and 156 to 348 (root). Ascomycota phylum was the most common species among all plant samples. The most significant classes identified were Lecanoromycetes and Dothideomycetes that differed significantly (p ≤ 0.05) according to their plant hosts and soil stress. The relative abundance of Pestalotiopsis (Sordariomycetes class) and Stereocaulon (Lecanoromycetes class) genera was influenced by the iron mining activities according to the leaf samples analysed. However, the abundance and wealth of endophytic fungal communities in A. grazielae from RCA were evidence that could explain their high resilience to environmental disturbances and the source-sink dynamics of fungal propagules

Principal coordinates analysis (PCoA) plots were generated for bacterial, fungal, and archaeal communities to visualize differences between the dry and rainy season and the four Cerrado physiognomies.

<p>Analysis of soil bacterial community structure based on (a) unweighted UniFrac distance and (b) Canberra distance; soil archaeal community structure based on (c) unweighted UniFrac distance and (d) Canberra distance; and soil fungal community structure based on (e) unweighted UniFrac distance and (f) Canberra distance. Markers represent replicate soil samples collected during the dry and rainy season in <i>cerrado denso</i> (CD, square), <i>campo sujo</i> (CS, circle), cerrado <i>sensu stricto</i> (SS, triangle), and gallery forest (MG, diamond) soils.</p