Free-living organisms frequently face shortage of macronutrients in natural environments, which are often poor in basic resources, such as carbon, nitrogen and phosphorus. Phosphorus occurs in nature in its maximal oxidized state (PO43-/Pi), which is also the preferred phosphorus source. Given the importance of Pi and the irregular availability of this nutrient in natural habitats, bacteria must be able to sense changes in Pi concentration in the environment and to modify the pattern of gene expression accordingly.
C. violaceum is a free-living β-proteobacterium that inhabits the soil and water of tropical environments, and that thrives in the acidic and low-nutrient waters of the Rio Negro in the Amazon basin. In this project we investigate the PHO regulon of C. violaceum strains. Some of these strains were isolated directly from the Rio Negro. The ability of these strains to take up Pi, and to express the PHO regulon genes is evaluated. In addition, we investigate the biochemistry of C. violaceum peculiar alkaline phosphatase.