Resumo

The implementation of policies and clean environmentally friendly techniques are necessary, and require monitoring programs, based on the quality and sustainability of the soil, to evaluate the success of different management practices. In this context, this study aimed at the evaluation of the bacterial community structure in soils under different land uses in the biome Cerrado, through a cultivation-independent molecular technique Terminal Restriction Fragment Length Polymorphism (T-RFLP). Soil samples were collected from ten sites comprising adjacent forest (AF), adjacent Cerrado (CE), pasture (PA), crop/livestock integration (CLIa and b), no-tillage (NTa, b and c) and conventional tillage (CT). Total DNA was extracted from samples and used as templates in PCR reaction using the universal primers labeled with fluorescence, for the 16S rRNA gene from bacterial group. The PCR-products were digested with the enzyme HhaI, and then the terminal fragments were read in an automatic sequencer ABI 3100. According to the data presented, statistical differences were observed for the richness of operational taxonomic units (OTUs) resulting in higher values in no-tillage (NTa) with soybean cultivated after wheat, followed by NTb and NTc cultived also with soybean after turnip and oat, respectively. The diversity analysis of Shannon Winner (H’) indicated that the forest and NTc presented an increase in diversity for bacterial community. Considering the rank of abundance among all treatments, the no-tillages samples were similar, and CLIa site presented some dominant specific bacterial groups. Redundancy Analysis (RDA) showed differences among the environments, separating the samples according to the soil land use. It was observed that V, SB, Mg, Na, Ca, P and K attributes usually differentiate management soils from forest soils, indicating that the manure addition to soil is the primary factor that affects the bacterial communities. The dendrogram indicated a high similarity among AF-CLIa-NTc-CE (57%) and among NTb-NTa-CT-PA-CLIb (64%). In conclusion, the bacterial diversity of AF soils was positively influenced. The agricultural land use in Cerrado showed clearly alteration in community structure and abundance of bacterial in soils. This change can affect some groups important for the ecosystem maintenance and function in soils.