The Influence of Different Land Uses on the Structure of Archaeal Communities in Amazonian Anthrosols Based on 16S rRNA and amoA Genes

Abstract

Soil from the Amazonian region is usually regarded as unsuitable for agriculture because of its low organic matter content and low pH; however, this region also contains extremely rich soil, the Terra Preta Anthrosol. A diverse archaeal community usually inhabits acidic soils, such as those found in the Amazon. Therefore, we hypothesized that this community should be sensitive to changes in the environment. Here, the archaeal community composition of Terra Preta and adjacent soil was examined in four different sites in the Brazilian Amazon under different anthropic activities. The canonical correspondence analysis of terminal restriction fragment length polymorphisms has shown that the archaeal community structure was mostly influenced by soil attributes that differentiate the Terra Preta from the adjacent soil (i.e., pH, sulfur, and organic matter). Archaeal 16S rRNA gene clone libraries indicated that the two most abundant genera in both soils were Candidatus nitrosphaera and Canditatus nitrosocaldus. An ammonia monoxygenase gene (amoA) clone library analysis indicated that, within each site, there was no significant difference between the clone libraries of Terra Preta and adjacent soils. However, these clone libraries indicated there were significant differences between sites. Quantitative PCR has shown that Terra Preta soils subjected to agriculture displayed a higher number of amoA gene copy numbers than in adjacent soils. On the other hand, soils that were not subjected to agriculture did not display significant differences on amoA gene copy numbers between Terra Preta and adjacent soils. Taken together, our findings indicate that the overall archaeal community structure in these Amazonian soils is determined by the soil type and the current land use.

The effects of rice-straw biochar addition on nitrification activity and nitrous oxide emissions in two Oxisols

“…4): the greater the biochar application rate, the greater the increase of gene copy number. These results are consistent with the findings that Terra Preta soils (which have high organic matter content due to the preColombian practice of slash and char agriculture, making them exceptionally fertile) contain higher amoA gene copy numbers than the adjacent soils (non-Terra Preta) (Taketani and Tsai, 2010). The positive response of ammonia oxidizers to biochar application may be related to its mineral components, including several macro-and micro-nutrients which are essential for microbial growth, as well as increased nutrient retention and availability in the soil and the adsorption of organic matter to the biochar surface (Lehmann and Joseph, 2009).…”

Land-use system shapes soil bacterial communities in Southeastern Amazon region

“…Despite its importance, the understanding of the consequences of the land-use change over microbial functional profile is still unclear. Only few studies in the Amazon forest region have explored the whole functional potential profile of soils microorganisms and specific functional diversity, such as aromatic hydrocarbon degradation gene (Brossi et al, 2014;Germano et al, 2012), and amoA gene (Navarrete et al, 2011;Taketani and Tsai, 2010). Further studies on microbial ecology in Amazon soils should rely on the functional profiles for a better understanding of the role of the microorganisms in the soil.…”

A Molecular Survey of the Diversity of Microbial Communities in Different Amazonian Agricultural Model Systems

“…These data were the first indication that diverse soil microbial populations have adapted to the unique biochemistry and physiological ecology of these anthrosols. On the other hand, the archaeal community observed in ADE sites presented lower richness and diversity than the adjacent soil [64].…”