title: Shifts in taxonomic and functional microbial diversity with agriculture: How fragile is the Brazilian Cerrado?
abstract: BACKGROUND
  The Cerrado--an edaphic type of savannah--comprises the second largest biome of the Brazilian territory and is the main area for grain production in the country, but information about the impact of land conversion to agriculture on microbial diversity is still scarce. We used a shotgun metagenomic approach to compare undisturbed (native) soil and soils cropped for 23 years with soybean/maize under conservation tillage--"no-till" (NT)--and conventional tillage (CT) systems in the Cerrado biome.
  
  
  RESULTS
  Soil management and fertilizer inputs with the introduction of agriculture improved chemical properties, but decreased soil macroporosity and microbial biomass of carbon and nitrogen. Principal coordinates analyses confirmed different taxonomic and functional profiles for each treatment. There was predominance of the Bacteria domain, especially the phylum Proteobacteria, with higher numbers of sequences in the NT and CT treatments; Archaea and Viruses also had lower numbers of sequences in the undisturbed soil. Within the Alphaproteobacteria, there was dominance of Rhizobiales and of the genus Bradyrhizobium in the NT and CT systems, attributed to massive inoculation of soybean, and also of Burkholderiales. In contrast, Rhizobium, Azospirillum, Xanthomonas, Pseudomonas and Acidobacterium predominated in the native Cerrado. More Eukaryota, especially of the phylum Ascomycota were detected in the NT. The functional analysis revealed lower numbers of sequences in the five dominant categories for the CT system, whereas the undisturbed Cerrado presented higher abundance.
  
  
  CONCLUSIONS
  High impact of agriculture in taxonomic and functional microbial diversity in the biome Cerrado was confirmed. Functional diversity was not necessarily associated with taxonomic diversity, as the less conservationist treatment (CT) presented increased taxonomic sequences and reduced functional profiles, indicating a strategy to try to maintain soil functioning by favoring taxa that are probably not the most efficient for some functions. Our results highlight that underneath the rustic appearance of the Cerrado vegetation there is a fragile soil microbial community.
authors.affiliation: Embrapa Soja, Soil Biotechnology, C.P. 231, 86001-970, Londrina, PR, Brazil.|Department Microbiology, Universidade Federal do Paraná, C.P. 19031, 81531-990, Curitiba, PR, Brazil.
authors.forename: Renata Carolini
authors.initials: RC
authors.lastname: Souza
authors.affiliation: Embrapa Cerrado, Soil Microbiology, C.P. 08223, 73301-970, Planaltina, DF, Brazil.
authors.forename: Iêda Carvalho
authors.initials: IC
authors.lastname: Mendes
authors.affiliation: Embrapa Cerrado, Soil Microbiology, C.P. 08223, 73301-970, Planaltina, DF, Brazil.
authors.forename: Fábio Bueno
authors.initials: FB
authors.lastname: Reis-Junior
authors.affiliation: LNCC, Labinfo, Av. Getúlio Vargas 333, 25651-071, Petrópolis, RJ, Brazil.
authors.forename: Fabíola Marques
authors.initials: FM
authors.lastname: Carvalho
authors.affiliation: Embrapa Soja, Soil Biotechnology, C.P. 231, 86001-970, Londrina, PR, Brazil.
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Nogueira
authors.affiliation: LNCC, Labinfo, Av. Getúlio Vargas 333, 25651-071, Petrópolis, RJ, Brazil.
authors.forename: Ana Tereza Ribeiro
authors.initials: AT
authors.lastname: Vasconcelos
authors.affiliation: Department Microbiology, Universidade Federal do Paraná, C.P. 19031, 81531-990, Curitiba, PR, Brazil.
authors.forename: Vânia Aparecida
authors.initials: VA
authors.lastname: Vicente
authors.affiliation: Embrapa Soja, Soil Biotechnology, C.P. 231, 86001-970, Londrina, PR, Brazil. mariangela.hungria@embrapa.br.
authors.forename: Mariangela
authors.initials: M
authors.lastname: Hungria
mesh_terms: D000383:Agriculture; D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D044822:Biodiversity; D001938:Brazil; D002244:Carbon / Q000032:analysis / Q000378:metabolism; D056186:Metagenomics; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism; D010802:Phylogeny; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology
chemical_list: D012987:Soil; D002244:Carbon; D009584:Nitrogen
keywords: Cerrado; Functional biodiversity; No-tillage; Shotgun metagenome; Soil management; Soil microbiome