Levantamento da comunidade bacteriana em diferentes tipos de solo impactados e não impactados por queimadas no Parque Nacional da Serra da Canastra – Minas Gerais

Abstract

The loss of diversity and habitats in areas of the Serra da Canastra National Park (PNSC) is a natural phenomenon due to natural lightning (lightning) burns, but has intensified due to anthropogenic burns. After the occurrence of fire, the areas take years to recover, depending, among other factors, on the soil bacterial microbiota. In this sense, the general objective of this work was to evaluate, according to the history of burning in certain areas of the PNSC, the diversity variations in the bacterial communities of the impacted and non-impacted soils during the 1st Integrated Fire Management (FIM). , in the Serra da Canastra National Park. For this purpose, soil samples from 8 different areas were used: (1) higher burn history; (2) lower history of burnings; (3) burned in the last year; (4) burned two years ago; (5) before burning - MIF; (6) after burning (downwind - collected approximately 30-40 minutes after burning); (7) before burning - MIF; (8) after burning (upwind - collected immediately after burning) and from them performed physicochemical characterization, soil diversity and microbiome analysis. In order to obtain a parameter of the effect of burning on the soil bacterial population, in order to observe the formation of clusters, a Principal Coordinate Analysis (PCoA) was carried out, showing that the area with the highest burning history is similar. the area before burning (no influence of burning for two years); Likewise, after burning, this same area still shows similarity between the areas, forming a cluster of similar sample richness similarities. In addition, the areas burned a year ago and two years ago also form groups that are more similar to each other. For a better understanding of the effect of fire on microbial communities, a Vegan package envfit function correlation test was performed versus the physicochemical variables with the axes of the Principal Coordinate Analysis (PCoA) where it was evidenced that the integrated management of fire did not cause significant differences in the physicochemical properties of soils in all studied areas. Regarding the phylogenetic composition of the studied areas, relative abundance was performed at Philo (97%), Class (86%), Order (64%), Family (50%) and Gender (21%) levels. Being found in greater relative abundance the members of the main bacterial phyla (Acidobacteria (29%), Proteobacteria (28%), Actinobacteria (19%). At genre level, a low number of sequences was classified (21%). most abundant genera: Acidibacter sp. (4%), Acidothermus sp. (3%), Bryobacter sp. (3%), Candidatus xiphinematobacter sp. (2%), Mycobacterium sp. (2%), Candidatus koribacter sp. ( 2%), Bradyrhizobium sp. (2%), Burkholderia sp. (1%), Isosphaera sp. (1%), Telmatobacter sp. (1%) and not being rated (75%). As a key group of soil quality bioindicators, Nitrogenase Reductase (nifH) (K02588) nitrogen-fixing bacteria were used as a key group of soil quality bioindicators. ) which predicts the abundance of gene families from phylogenetic markers Thus, using the 16S rRNA microbiome technique, it was found that the abundance of predicted Operating Taxonomic Units (OTUs) that have the nifH gene (K02588) was less than 0.001% of the total predicted genes for all samples studied. . It was observed that, in the studied samples, genera that have the nifH gene (K02588) are found in all areas and in the soil layers (0-10cm) and (10-20cm) analyzed. The bacterial groups of the genera Bradyrhiobium sp., Burkholderia sp., Kaistobacter sp., Pedomicrobium sp., Phormidium sp. and Rhodoplanes sp. From the analysis of the studied areas, it was observed that there was a decrease or inactivation of the genera Kaistobacteria sp. and Phormidium sp. after the passing of the fire. However, the nitrogen fixation group remained present. Thus, the present study through the microbiome technique showed that the soil microbiota composition in relation to the areas with distinct burn histories and before and after the FIM remained similar, thus it should be emphasized the efficiency of the integrated fire management technique. as it ensures soil quality by not causing significant impacts on the microbial community and does not significantly alter the physicochemical properties of the soil and is crucial for preventing accidental or criminal forest fires and preserving biodiversity. Finally, it is noteworthy that, although the molecular analyzes of this work did not show alteration in the richness of the communities of the different studied areas with different burning times and in Integrated Fire Management, fire can have a pronounced impact on moisture, nutrient decrease. , soil temperature and pH, resulting in changes in the structure of the metabolically active microbial community. Further studies on the actual impact of fire on the Cerrado soil microbiota are needed, since the microbiome technique does not allow us to visualize the groups of metabolically active microorganisms, as well as to find us with different soil types in the Cerrado biome. makes our comparison difficult.