Free-Living Enterobacterium Pragia fontium 24613: Complete Genome Sequence and Metabolic Profiling

Abstract

Pragia fontium is one of the few species that belongs to the group of atypical hydrogen sulfide-producing enterobacteria. Unlike other members of this closely related group, P. fontium is not associated with any known host and has been reported as a free-living bacterium. Whole genome sequencing and metabolic fingerprinting confirmed the phylogenetic position of P. fontium inside the group of atypical H₂S producers. Genomic data have revealed that P. fontium 24613 has limited pathogenic potential, although there are signs of genome decay. Although the lack of specific virulence factors and no association with a host species suggest a free-living style, the signs of genome decay suggest a process of adaptation to an as-yet-unknown host.

Keywords: Enterobacteriaceae; Pragia fontium; free-living bacteria; phylogeny; whole genome sequence.

Figure 1.

Phylogenetic position of the genus Pragia based on a whole genome sequence tree. Only the relevant part of the Enterobacteriaceae tree is shown (the whole tree is depicted in Figure S2). All branches are supported with high bootstrap values. The tree was drawn to scale; the scale bar represents the estimated number of amino acid changes per site per unit of branch length.

Figure 2.

The Venn diagram represents the core genome and pangenome of Pragia and the closely related atypical H₂S producers. The numbers represent the gene clusters shared by corresponding group of genera. The diagram shows the close relationships among those inside the group of atypical H₂S producers.