Microbial communities and functional genes involved in nutrient cycling of Pantanal of Nhecolândia MS

• Autor(a) principal: Pellegrinetti, Thierry Alexandre
• Data de Publicação: 2022
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/64/64133/tde-29092022-155448/
• topic: Biogeochemical cycles; Ciclos biogeoquímicos; Cyanobacterial blooms; Ecologia microbiana; Florações de cianobactéria; Metagenomic; Metagenômica; Microbial ecology

Nhecolândia (MS), one important sub-region of the Pantanal, consists of 12,150 lakes among which approximately 600 lakes can be described as saline alkaline (soda lakes). Soda lakes present high concentrations of carbonates and sodium bicarbonates, resulting in high pH (above 9) and salinities (up to 35 mS cm-1). Even under hostile conditions, this ecosystem hosts a rich biodiversity of microorganisms. In this study, an approach that included molecular and chemical analyses was used to evaluate the composition (taxonomic and functional) and lifestyle of bacterial communities in the surface water of this environment. Through ordination analysis using limnological and metagenomic data, it was possible to group the soda lakes into three distinct profiles: eutrophic turbid (ET), oligotrophic turbid (OT) and clear vegetated oligotrophic (CVO). Seasonality was a crucial factor in the dynamics of the bacterial community. During the dry season, the water level reduced drastically due to intense evaporation periods, leading to an increase in salinity, pH and nutrient concentration, which in turn enhanced the diversity and relative abundance of microorganisms. This scenario led to the predominance of cyanobacterial blooms in ET lakes, mainly associated with Artrospira platensis or Anabaenopsis elenkinii. This predominance could be justified by the investment in mechanisms of nutrient acquisition by these organisms. In the OT and CVO lakes, there was a predominance of Actinobacteria, Alphaproteobacteria and Betaproteobacteria and these organisms possibly adopted strategies associated with nutrient uptake. It is interesting to note that nutrient acquisition genes were predominant in ET lakes, with high relative abundance of genes associated with biological fixation of CO2, N2, alkaline phosphatase and sulfate reduction. In OT and CVO lakes, we observed a higher abundance of low frequent processes such as nitrification and methanogenesis while genes associated with nitrate and nitrite reduction, and denitrification were more abundant. Moreover, the OT and CVO lakes presented prevalence of genes related to phosphate transport, phosphorus regulation as well as oxidation of sulfide and thiosulfate. Altogether, this study illustrates the taxonomic and functional diversity in tropical soda lakes, as well as how microorganisms behave under distinct environmental conditions. Moreover, the dataset obtained in this study may provide guidelines for management practices and conservation of the Pantanal\'s biodiversity