Characterization of the diazotrophic bacterial communities structure in phyllosphere, rhizosphere and litter of arboreal species of the Amazon Rainforest

Abstract

The Amazon rainforest is one of the most biodiverse tropical biomes with global ecological implications. Therefore, efforts to understand this biome are of great importance. The microbiota of the Amazon rainforest plays an indispensable role in the accomplishment of numerous biogeochemical processes, such as nutrient cycling, degradation of organic matter, and others. However, the structuring of microbial communities and the factors that determine this structure is poorly known. It has been observed in the Atlantic Forest that the structure of the bacterial communities in the phyllosphere, dermosphere and rhizosphere depends on the vegetal taxon and are distinct from each other. In addition, biological nitrogen fixation (BNF) may be a key activity in this environment. The FBN of free-living bacteria associated with the Atlantic Forest plant species can contribute 80-240 kg of N/ha.year, according to estimates that were revised based on the new calculations. These data suggest higher nitrogen inputs than those previously reported in the scientific literature. However, the microorganisms involved in BNF in the Amazon are not known, as well as the factors that affect the structuring of the communities of these diazotrophs. This study intends to evaluate the structure of diazotrophic microorganisms communities associated with phyllosphere, rhizosphere and litter of different tree species of the Amazon Forest. Samples of leaves, litter and rhizospheric soil of 9 tree species were collected at the experimental station at Km 67 of the Tapajós FLONA, at three different time periods. Total DNA from each sample was extracted for sequencing of diazotrophs nifH gene. The community structures and diazotrophic diversity will be compared to determine if the structuring of these communities is dependent on the vegetal taxon, as in the Atlantic Forest, and what are the possible factors that affect its organization. (AU)