Microbial Diversity in Cerrado Biome (Neotropical Savanna) Soils

Abstract

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 of AD3, WPS-2, Planctomycetes, Thermoprotei, and Glomeromycota typically decreased in 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.

Archaea in Natural and Impacted Brazilian Environments

“…Although chromatographic data revealed relatively high concentrations of methane in these soil samples, only 2% of all archaeal sequences were affiliated to the methanogenic organism Methanosarcina acetivorans, while 56% of all archaeal sequences detected were classified as uncultivated Crenarchaeota and 42% were affiliated to the Thaumarchaeota Candidatus Nitrososphaera gargensis. As observed for other soils [99, 117], archaeal richness and diversity values were significantly lower than those found for bacteria in the sedimentary soils from this petroliferous basin [118]. In another study, the effect of petroleum contamination on microbial communities from Trindade Island coastal soils were analyzed by microcosm experiments [119].…”

“…Recently, high-throughput sequencing of ribosomal markers and shotgun metagenomic analyses were combined to investigate bacterial, fungal, and archaeal communities in soils of four different phytophysiognomies from Cerrado during the dry and rainy seasons [99]. Most of the archaeal sequences detected in soils from three vegetation physiognomies (Campo Sujo, Cerrado sensu stricto and Mata de Galeria) in both seasons were affiliated to Crenarchaeota and classified as Thermoprotei.…”

“…Thus, probably some of the sequences classified as Thermoprotei are actually affiliated to lineages that are increasingly detected in mesophilic environments but that still have unstable taxonomic classifications. The phylum Thaumarchaeota was the most abundant in soils from Cerrado Denso in both rainy and dry seasons and although sequences affiliated to Methanomicrobia were found in this phytophysiognomy during the rainy season, they were absent in the dry season samples [99]. …”

Neotropical seasonally dry forests: response of soil fungal communities to anthropogenic actions

“…The diversity index values suggested by Ferreira de Araujo et al, 41 were higher than the ones shown by 53. Pereira de Castro et al, 42 and a higher fungal diversity was observed in campo graminoide than in Cerrado forests. In addition, several studies have shown that structural changes in the fungal community were in response to different soil managements.…”

Structure of Fungal Communities in Sub-Irrigated Agricultural Soil from Cerrado Floodplains

“…The physical, chemical and biological attributes of the soil are affected by several conditions related to the type of soil preparation used in each management system; the effects on these attributes are dependent on the intensity of soil disturbance, traffic of farm tractors, type of equipment used, management of plant waste, and moisture conditions in the soil at the time of tillage [8]. Despite previous findings in areas of the Cerrado biome [9][10][11], there is a lack of information about the impact of soil agricultural management on the fungal microbial community in Cerrado areas.…”