Diminuição da diversidade microbiana de solos em áreas sob arenização no bioma Pampa brasileiro

Abstract

Soil “sandification” is a natural process where, over the years, large amounts of soil, become sand due to the weathering and anthropic actions. This process completely changes the local edaphic characteristics including the vegetation. This changes might affect the soil microbial community causing losses of biodiversity. The objective of this work was to describe the effects of this erosive process on the soil microbiota by comparing soil samples from a sand patch with soil samples from natural grassland in the Brazilian pampa. The study was conducted in two sites under similar environmental conditions located at the Brazilian Pampa in Quaraí and Cacequi municipalities. Soil samples were collected in triplicate in a sand patch area and natural grassland. From each sample 0.25g of soil was used for total DNA isolation using the DNA PowerSoil kit (MoBio laboratories, Inc.). The 16S rRNA gene (V4 region) was amplified and sequenced by using Next Generation Sequencing. Sequences were processed by using the pipeline of the Brazilian Microbiome Project and library comparisons were performed using Qiime package. A total of 3,245 OTUs grouped at 97% cutoff sequence similarity were detected in soil samples under “sandification” while 9,535 OTUs were detected in the grassland. The OTUs were classified in 20 microbial phyla. Acidobacteria and Actinobacteria were the most abundant in both sampling places making up 19.9% and 20% of the total microbial community respectively. Shannon diversity index also indicated low microbial diversity in soil samples under “sandification” (8.4) compared to the natural grassland (10.5). In line with the results observed for alpha diversity, the analysis of beta diversity showed that the microbial community structure were different between both places. Altogether the results indicate that this erosion processes is causing the loss of microbial diversity and altering the overall microbial structure.