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Bordetella avium is a pathogen of poultry and is phylogenetically distinct from Bordetella bronchiseptica, Bordetella pertussis, and Bordetella parapertussis, which are other species in the Bordetella genus that infect mammals. In order to understand the evolutionary relatedness of Bordetella species and further the understanding of pathogenesis, we obtained the complete genome sequence of B. avium strain 197N, a pathogenic strain that has been extensively studied. With 3,732,255 base pairs of DNA and 3,417 predicted coding sequences, it has the smallest genome and gene complement of the sequenced bordetellae. In this study, the presence or absence of previously reported virulence factors from B. avium was confirmed, and the genetic bases for growth characteristics were elucidated. Over 1,100 genes present in B. avium but not in B. bronchiseptica were identified, and most were predicted to encode surface or secreted proteins that are likely to define an organism adapted to the avian rather than the mammalian respiratory tracts. These include genes coding for the synthesis of a polysaccharide capsule, hemagglutinins, a type I secretion system adjacent to two very large genes for secreted proteins, and unique genes for both lipopolysaccharide and fimbrial biogenesis. Three apparently complete prophages are also present. The BvgAS virulence regulatory system appears to have polymorphisms at a poly(C) tract that is involved in phase variation in other bordetellae. A number of putative iron-regulated outer membrane proteins were predicted from the sequence, and this regulation was confirmed experimentally for five of these.

Results reveal that the aquaporin transcription increases at the stationary growth phase of Escherichia coli grown on a variety of media. Further, the expression of the porin is not affected by up- or downshifts in osmolality.

The overexpression of the Bradyrhizobium japonicum lrp homolog complemented delta-aminolevulinic acid (ALA) and dipeptide uptake activities in Escherichia coli dpp mutants. The effects of the Bradyrhizobium japonicum gene which encoded a peptide or ALA transporter in Escherichia coli dpp mutants indicated the presence of an Dpp-independent ALA uptake activity. Furthermore, the constitutive expression of lrp inhibited ALA uptake in cells due to the negative effector activity of the Lrp homolog on cellular transport.

A strain of Bradyrhizobium japonicum that lacks the gene for proline biosynthesis cannot develop nodules on soybeans and cannot fix nitrogen. This indicates that the proline provided by the host plant is not sufficient and therefore must not be the only energy source for the bacterium.