Genomic and evolutionary comparisons of diazotrophic and pathogenic bacteria of the order Rhizobiales

Abstract

BackgroundSpecies belonging to the Rhizobiales are intriguing and extensively researched for including both bacteria with the ability to fix nitrogen when in symbiosis with leguminous plants and pathogenic bacteria to animals and plants. Similarities between the strategies adopted by pathogenic and symbiotic Rhizobiales have been described, as well as high variability related to events of horizontal gene transfer. Although it is well known that chromosomal rearrangements, mutations and horizontal gene transfer influence the dynamics of bacterial genomes, in Rhizobiales, the scenario that determine pathogenic or symbiotic lifestyle are not clear and there are very few studies of comparative genomic between these classes of prokaryotic microorganisms trying to delineate the evolutionary characterization of symbiosis and pathogenesis.ResultsNon-symbiotic nitrogen-fixing bacteria and bacteria involved in bioremediation closer to symbionts and pathogens in study may assist in the origin and ancestry genes and the gene flow occurring in Rhizobiales. The genomic comparisons of 19 species of Rhizobiales, including nitrogen-fixing, bioremediators and pathogens resulted in 33 common clusters to biological nitrogen fixation and pathogenesis, 15 clusters exclusive to all nitrogen-fixing bacteria and bacteria involved in bioremediation, 13 clusters found in only some nitrogen-fixing and bioremediation bacteria, 01 cluster exclusive to some symbionts, and 01 cluster found only in some pathogens analyzed. In BBH performed to all strains studied, 77 common genes were obtained, 17 of which were related to biological nitrogen fixation and pathogenesis. Phylogenetic reconstructions for Fix, Nif, Nod, Vir, and Trb showed possible horizontal gene transfer events, grouping species of different phenotypes.ConclusionsThe presence of symbiotic and virulence genes in both pathogens and symbionts does not seem to be the only determinant factor for lifestyle evolution in these microorganisms, although they may act in common stages of host infection. The phylogenetic analysis for many distinct operons involved in these processes emphasizes the relevance of horizontal gene transfer events in the symbiotic and pathogenic similarity.

The Role of the Microbiome of Truffles in Aroma Formation: a Meta-Analysis Approach

“…A tempting hypothesis is that truffle fruiting bodies would be more than a habitat for bacteria and that mutualistic interactions might occur between the fungi and their microbiota. Some members of the Rhizobiales order are well known for their ability to fix atmospheric nitrogen either as freeliving organisms or in symbiosis with plants (26). Barbieri et al (27) demonstrated that nitrogen fixation occurs inside fruiting bodies of the white truffle T. magnatum.…”

Evolutionary transitions in bacterial symbiosis

“…Along with the evolution and diversification of animals and plants, the past 500 million years have also witnessed a massive radiation of bacteria. Bacterial lineages have evolved diverse mechanisms to gain entry and proliferate in the tissues and cells of multicellular eukaryotes (1)(2)(3)(4), and these symbionts vary in their effect on hosts from harmful to beneficial (3,4). Archaea have also evolved associations with hosts, but these interactions do not appear as diverse or ubiquitous.…”

“…Bacterial mutualists are diverse (1)(2)(3)(4)(9)(10)(11)(12) and exhibit a variety of lifestyles and coevolutionary relationships with eukaryote hosts (8) (Table 1). First, beneficial bacteria vary in their degree of reliance on hosts for reproduction.…”

Next-Generation Pyrosequencing Analysis of Microbial Biofilm Communities on Granular Activated Carbon in Treatment of Oil Sands Process-Affected Water

“…Ozonation decreased the Rhizobiales composition in the planktonic OSPW, while they were still dominant in the biofilm samples. The members of Rhizobiales have diverse functions, including atmospheric nitrogen fixation by living symbiotically in the roots of leguminous plants (55,56). The other dominant orders of Alphaproteobacteria were Rhodospirillales and Rhodobacterales (Fig.…”