The Rcs-Regulated Colanic Acid Capsule Maintains Membrane Potential in serovar Typhimurium.

The Rcs phosphorelay and Psp (phage shock protein) systems are envelope stress responses that are highly conserved in gammaproteobacteria. The Rcs regulon was found to be strongly induced during metal deprivation of serovar Typhimurium lacking the Psp response. Nineteen genes activated by the RcsA-RcsB response regulator make up an operon responsible for the production of colanic acid capsular polysaccharide, which promotes biofilm development.

Membrane vesicles are immunogenic facsimiles of Salmonella typhimurium that potently activate dendritic cells, prime B and T cell responses, and stimulate protective immunity in vivo.

Gram-negative bacteria produce membrane vesicles (MVs) from their outer membrane during growth, although the mechanism for MV production and the advantage that MVs provide for bacterial survival in vivo remain unknown. MVs function as an alternate secretion pathway for Gram-negative bacteria; therefore, MV production in vivo may be one method by which bacteria interact with eukaryotic cells. However, the interactions between MVs and cells of the innate and adaptive immune systems have not been studied extensively.

Methylotenera mobilis gen. nov., sp. nov., an obligately methylamine-utilizing bacterium within the family Methylophilaceae.

A novel obligate methylamine utilizer (strain JLW8(T)), isolated from Lake Washington sediment, was characterized taxonomically. The isolate was an aerobic, Gram-negative bacterium. Cells were rod-shaped and motile by means of a single flagellum.

Methyloversatilis universalis gen. nov., sp. nov., a novel taxon within the Betaproteobacteria represented by three methylotrophic isolates.

The taxonomic positions and phylogenetic relationships of two new methylotrophic isolates from Lake Washington (USA) sediment, FAM5T and 500, and the previously described methylotrophic strain EHg5 isolated from contaminated soil in Estarreja (Portugal) were investigated. All three strains were facultative methylotrophs capable of growth on a variety of C1 and multicarbon compounds. Optimal growth occurred at pH 7.

Involvement of the S-layer proteins Hpi and SlpA in the maintenance of cell envelope integrity in Deinococcus radiodurans R1.

The potential functions have been investigated of two proteins in Deinococcus radiodurans R1 predicted to be involved in the maintenance and integrity of the S layer: the hexagonally packed intermediate (Hpi) protein, and SlpA (DR2577), a homologue of an S-layer SlpA protein in Thermus thermophilus. Deletion of the hpi gene had little effect on the structure of the cell envelope or on shear- or solvent-induced stress responses. However, deletion of the slpA gene caused substantial alterations in cell envelope structure, and a significant defect in resistance to solvent and shear stresses compared to the wild-type.

Methylosarcina lacus sp. nov., a methanotroph from Lake Washington, Seattle, USA, and emended description of the genus Methylosarcina.

An obligately methanotrophic bacterial strain, LW14T, isolated from the sediment of Lake Washington, Seattle, USA, is described taxonomically. The isolate is an aerobic, Gram-negative, non-motile bacterium capable of growth on methane, and possesses type I intracytoplasmic membranes (i.e.

Labrys methylaminiphilus sp. nov., a novel facultatively methylotrophic bacterium from a freshwater lake sediment.

A new bacterial isolate from a methylamine enrichment culture is described, representing a novel species of facultatively methylotrophic bacteria. The non-motile bacterium is Gram-negative, replicates by budding and does not form endospores. The isolate utilizes methylated amines, as well as a variety of monosaccharides, disaccharides, amino acids, organic acids, aromatic compounds and alcohols as substrates, but does not utilize methanol.