Molecular ecology and biodiversity of Roseobacter group of the Southwest Atlantic

Abstract

Rhodobacteraceae is one of the most abundant families of Alphaproteobacteria ever described and has a high phenotypic and ecological diversity. Within the Rhodobacteraceae family, the Roseobacter group has stood out due to its abundance and metabolic versatility in marine ecosystems. Occurrence studies using 16S rRNA gene sequencing have shown that its abundance often corresponds to 10 to 25% of the microbial community in pelagic marine ecosystems, thus being one of the most abundant groups of marine heterotrophic bacteria. Despite the high genomic diversity, the Roseobacter clade is well established in the Alphaproteobacteria phylogenetic tree. However, the internal phylogeny of the group based on 16S rRNA genes is not as robust, with some remarkably paraphyletic strains within the clade. The inclusion of non-cultivable members in phylogenomic analyzes represents a computational challenge that needs to be solved to understand the evolutionary history of the group. The pangenome approach and the implementation of pipelines that use large-scale phylogenetic profiles of genomes and metagenomes will be used in this proposal to identify and compare common and unique genes for each lineage and reconstruct the phylogeny of the group and recognize dispersion to patterns to the Southwest Atlantic. The study of the diversity of the 16S rRNA gene of the Roseobacter group and the reconstruction of genomes in the Brazilian Southwest Atlantic to be carried out in shelf and slope areas, will bring a panorama never studied for the Roseobacter group for this region. The use and development of skills in cultivation approaches, phylogenomics and bioinformatics of this project, targeting the marine Roseobacter group, will be fundamental for the formation of the first collection of marine Roseobacter collection in Brazil and a database and metadata that do not yet exist that will constitute the thematic collection of the Brazilian Microbiome Project. Thus, this project aims to contribute to the unprecedented knowledge of the pattern, dispersion and phylogenetic and functional diversity of Roseobacter in bacterioplankton and sediments of the Southwest Atlantic; contribute to the review of the phylogeny and description of the group's paraphyletic genera, establish the first collection of marine bacteria of the Roseobacter group in Brazil and start the construction of the Brazilian Microbiome Project marine microbiome thematic bank. (AU)