The chimeric nature of the genomes of marine magnetotactic coccoid‐ovoid bacteria defines a novel group ofProteobacteria

Abstract

Magnetotactic bacteria (MTB) are a group of phylogenetically and physiologically diverse Gram-negative bacteria that synthesize intracellular magnetic crystals named magnetosomes. MTB are affiliated with three classes of Proteobacteria phylum, Nitrospirae phylum, Omnitrophica phylum and probably with the candidate phylum Latescibacteria. The evolutionary origin and physiological diversity of MTB compared with other bacterial taxonomic groups remain to be illustrated. Here, we analysed the genome of the marine magneto-ovoid strain MO-1 and found that it is closely related to Magnetococcus marinus MC-1. Detailed analyses of the ribosomal proteins and whole proteomes of 390 genomes reveal that, among the Proteobacteria analysed, only MO-1 and MC-1 have coding sequences (CDSs) with a similarly high proportion of origins from Alphaproteobacteria, Betaproteobacteria, Deltaproteobacteria and Gammaproteobacteria. Interestingly, a comparative metabolic network analysis with anoxic network enzymes from sequenced MTB and non-MTB successfully allows the eventual prediction of an organism with a metabolic profile compatible for magnetosome production. Altogether, our genomic analysis reveals multiple origins of MO-1 and M. marinus MC-1 genomes and suggests a metabolism-restriction model for explaining whether a bacterium could become an MTB upon acquisition of magnetosome encoding genes.

Genomic study of a novel magnetotacticAlphaproteobacteriauncovers the multiple ancestry of magnetotaxis

“…So far, cultured and uncultured MTB A from freshwater and marine environments belong to the following three genera within a single family: the Magnetospirillum, Magnetovibrio and Magnetospira genera within the Rhodospirillales (Lefèvre et al, 2013a). Indeed, recent comparative genomic analyses concluded that Magnetococcalesonce classified in Alphaproteobacteriashall be considered as a new class of Proteobacteria (i.e., "Candidatus Etaproteobacteria") (Ji et al, 2017;Lin et al, 2018). In the Alphaproteobacteria class, phylogenies based on neutral markers rather support the scenario of a clonal inheritance of magnetosome genes within and between genera (Lefèvre et al, 2013a), despite the genetic evidences compatible with HGTs found in some MTB A genomes (Jogler et al, 2009;Rioux et al, 2010).…”

Comparative Genome Analysis Provides Insights into Both the Lifestyle of Acidithiobacillus ferrivorans Strain CF27 and the Chimeric Nature of the Iron-Oxidizing Acidithiobacilli Genomes

“…Similar analyses have been performed in the genomes of Alphaproteobacteria (Esser et al, 2007), and great variation in the data (between 33 and 97%) pointed out a chimeric trait of several alphaproteobacterial genomes. In addition, this strategy, combines to other evolutionary analyses, has been recently used to define a novel group of Proteobacteria, named Etaproteobacteria (Ji et al, 2017). These current data demonstrated, for the first time, that the top-scoring Blast analysis can be useful to define or confirm that a set of organisms belong to a particular taxonomic groups.…”

Spatial Pattern of Bacterial Community Diversity Formed in Different Groundwater Field Corresponding to Electron Donors and Acceptors Distributions at a Petroleum-Contaminated Site

“…More than 10 OTUs corresponded to this bacterium. The function of this bacterium is not well defined; it was previously identified in an anammox community [60] and might be related to Magnetotactic bacteria [61]. Samples PM7 and OTA4 were associated with high NO 3 − and low Mn 2+ , which suggests that these samples were in the denitrification phases.…”