A Global Metabolic Shift Is Linked to Salmonella Multicellular Development

Bacteria can elaborate complex patterns of development that are dictated by temporally ordered patterns of gene expression, typically under the control of a master regulatory pathway. For some processes, such as biofilm development, regulators that initiate the process have been identified but subsequent phenotypic changes such as stress tolerance do not seem to be under the control of these same regulators. A hallmark feature of biofilms is growth within a self-produced extracellular matrix. In this study we used metabolomics to compare Salmonella cells in rdar colony biofilms to isogenic csgD deletion mutants that do not produce an extracellular matrix. The two populations show distinct metabolite profiles. Even though CsgD controls only extracellular matrix production, metabolite signatures associated with cellular adaptations associated with stress tolerances were present in the wild type but not the mutant cells. To further explore these differences we examine the temporal gene expression of genes implicated in biofilm development and stress adaptations. In wild type cells, genes involved in a metabolic shift to gluconeogenesis and various stress-resistance pathways exhibited an ordered expression profile timed with multicellular development even though they are not CsgD regulated. In csgD mutant cells, the ordered expression was lost. We conclude that the induction of these pathways results from production of, and growth within, a self produced matrix rather than elaboration of a defined genetic program. These results predict that common physiological properties of biofilms are induced independently of regulatory pathways that initiate biofilm formation

Antibiotic resistance in swarming salmonella

Bibliography: p. 97-11

Long-Term Survival of Salmonella enterica Serovar Typhimurium Reveals an Infectious State That Is Underrepresented on Laboratory Media Containing Bile Salts▿

Cells in desiccated Salmonella enterica serovar Typhimurium rdar (red, dry, and rough) morphotype colonies were examined for culturability and infectivity after 30 months. Culturability decreased only 10-fold; however, cells were underrepresented on Salmonella selective media containing bile salts. These cells were mildly attenuated compared to the infectivity of freshly grown cells but still able to cause systemic infections in mice

Influence of Swift Heavy Ions on Electric and Magnetotransport

Секция 3. Модификация свойств материалов = Section 3. Modification of Material PropertiesIn the present paper we report about the influence of Swift Heavy Ions (SHI) irradiation on the electric and magnetotransport in the antimony (Sb) δ-layer in silicon. Temperature and magnetic field dependences of the sheet resistance R(T, B) in the temperature range 2 < T < 300 K and magnetic field induction B up to 8 T before and after the 167 MeV Xe+26 ion irradiation with ion fluences since 1×10 8 cm-2 to 5×10 10 cm-2 were measured. It was detected strong role of quantum corrections on low-temperature R(T, B)