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

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.

Complete Genome Sequence of Pragia fontium 24613, an Environmental Bacterium from the Family Enterobacteriaceae.

The complete genome sequence of Pragia fontium 24613 was determined using PacBio RSII, Roche 454, and SOLiD sequencing. A total of 3,579 genes were predicted, including 3,338 protein-coding sequences and 146 pseudogenes. This is the first whole-genome sequence of a strain belonging to the environmental genera of the family Enterobacteriaceae.

Experimental administration of the probiotic Escherichia coli strain Nissle 1917 results in decreased diversity of E. coli strains in pigs.

The strain Escherichia coli Nissle 1917 (EcN) is widely used as an efficient probiotic in therapy and prevention of human infectious diseases, especially of the intestinal system. Concurrently, small adult pigs are being used as experimental omnivore models to study human gastrointestinal functions. EcN bacteria were applied to 6 adult healthy female pigs in a 2-week trial. 6 Control animals remained untreated. Altogether, 164 and 149 bacterial strains were isolated from smear samples taken from gastrointestinal mucosa in the experimental and control group, respectively. Each individual E. coli strain was then tested for the presence of 29 bacteriocin-encoding determinants as well as for DNA markers of A, B1, B2 and D phylogenetic groups. A profound reduction of E. coli genetic variance (from 32 variants to 13 ones, P = 0.0006) was found in the experimental group, accompanied by a lower incidence of bacteriocin producers in the experimental group when compared to control (21.3 and 34.9%, respectively; P = 0.007) and by changes in the incidence of individual bacteriocin types. The experimental administration of EcN strain was not sufficient for stable colonization of porcine gut, but induced significant changes in the enterobacterial microbiota.