Changes in land use alter the structure of bacterial communities in Western Amazon soils

Abstract

Here we show how agricultural practices by indigenous peoples as well as forest recovery relate to the structure and composition of Amazon soil bacterial communities. Soil samples were collected in different land use systems and bacterial community composition and diversity were explored by T-RFLP, cloning and sequencing, and data were analyzed with multivariate techniques. The main differences in bacterial community structure were related to changes in the soil attributes that, in turn, were correlated to land use. Community structure changed significantly along gradients of base saturation, [Al 3 þ ] and pH. The relationship with soil attributes accounted for about 31% of the variation of the studied communities. Clear differences were observed in community composition as shown by the differential distribution of Proteobacteria, Bacteroidetes, Firmicutes, Acidobacteria and Actinobacteria. Similarity between primary and secondary forest communities indicates the recovery of bacterial community structure during succession. Pasture and crop soil communities were among the most diverse, showing that these land use types did not deplete bacterial diversity under the conditions found in our sites.

Bacterial Communities in the Rhizosphere of Biofuel Crops Grown on Marginal Lands as Evaluated by 16S rRNA Gene Pyrosequences

“…Recent results in the literature indicate that plant diversity may not be directly related to diversity in soil bacterial communities [4,6,9] and that soil variables may play a more important role [4,9]. Thus, a possible explanation for the results that we observed may be that changes in the soil environment, such as the increase in pH in the agricultural sites, favor an increase in bacterial diversity.…”

“…On the other hand, East Lansing and LC biofuel soil communities formed a separate group associated with higher P and K concentrations and lower pH, Ca, and salt concentrations. Forest communities were correlated to higher NH 4 + concentration and organic matter content. Among those communities, UP communities were associated with higher pH, Ca, and salt concentrations, and other forest communities are related to lower values of those variables.…”

Diversity and Efficiency of Rhizobia Communities from Iron Mining Areas Using Cowpea as a Trap Plant

“…During the experiment, the temperature in the greenhouse reached 46 °C, which may have negatively affected nodulation in some treatments. Soil chemical properties may also have affected nodulation of some treatments, especially those related to acidity and low concentration of nutrients, which may negatively affect microbiota (Moreira, 2006;Jesus et al, 2009;Lima et al, 2009). From the 16S rRNA gene partial sequencing, free-living, associative, and symbiotic N 2 -fixing bacteria that act as plant growth promoters were identified, in addition to other genera commonly isolated from nodules.…”

“…These microorganisms have an important role in nutrient cycling and in improving nutrient availability, which favors the establishment of plants. They also show potential as indicators of environment changes, such as in pH, Al 3+ contents, and organic matter, which are the factors that most influence the occurrence of microorganisms in the soil (Powlson et al, 1987;Siqueira et al, 1994;Lauber et al, 2008;Jesus et al, 2009). …”

Fungal Community Structure as an Indicator of Soil Agricultural Management Effects in the Cerrado

“…Several studies have highlighted soil management as an important factor influencing soil microbiota structure (Jesus et al, 2009;Taketani and Tsai, 2010;Navarrete et al, 2011). However, the mechanisms involved in changes in soil microbial communities are not yet fully understood (He et al, 2012).…”