Avaliação da diversidade genética da comunidade planctônica de reservatórios de água doce tropicais, através de análise metagenômica

Abstract

On the first chapter we present the diversity of picocyanobacteria in the Volta Grande reservoir, through classic taxonomy, complemmentary statistical analyses and metagenomics approach. The richness in morphologically described species was in line with the microdiversity observed in the dominant genera annotated, according to reference databases: NCBI (nt) e SILVA (ssu rRNA). On the second chapter se see the metagenomic profile of the Marimbondo reservoir, both in spacial and temporal scale. The environmental variables showed a gradient consistent with the increase of biomass in the Microcystis population. The taxonomic profile of the community was different between samples with low or high Microcystis biomass, as well as correlated with the environmental gradient. Meanwhile, the functional profile was stable among samples, indicating functional redundancy. Therefore, the distinct taxonomic annotations could actually reflect the diversification/adaptation dynamics of the gene pool in a given population. The third chapter is concerned with the microdiversity of the M. aeruginosa population in the the Marimbondo reservoir, due to number of strains previously observed. The recruitment analyses and variant calling (SNV) were used with the intent of exploring alignment patterns and differentiation among population members. The microdiversity we observed could be related to the mosaic-like genomic structure in which the gene pool alternates according to the functional needs of the population. The fourth chapter explores the genetic variability of the two genera of the Aphanizomenonaceae Family in Pampulha lake, an urban artificial hypereutrophic reservoir suffering the impact of constant cyanobacteria blooms. Through different approaches, we explored the complexity in closely related strains and genera. The alignment of south american strains and genera indicated greater similarity of the local population with the genomes of Raphidiopsis brookii D9 and Cylindrospermopsis raciborskii T3. Many factors might indicate that we are dealing with a still unknown population, among which is the lack of full alignment with R. brookii D9, the similarity with several south american sequences and the high intraspecific diversity. Said diversity was observed through the wide distribution in SNVs, especially those detected in assimilation and conversion of nitrite/nitrate operons.