Ramón Bonet

Removal of uranium by an exopolysaccharide from Pseudomonas sp.

SummaryAccumulation of uranium (U) is reported for isolated exopolysaccharide produced by Pseudomonas sp. EPS-5028. A maximum uptake of 96 μg U/mg polymer was observed. In contrast, the maximum accumulation of uranium by deacylated polysaccharide was 46 μg/mg. This metal-complexing capacity observed suggests that the anionic reactive sites on the structure could be responsible for this activity. Metal uptake was affected by pH and was not affected by temperature. Expolysaccharide from Pseudomonas sp. EPS-5028 obeyed the Freundlich isotherm indicating single layer adsorption.

Occurrence of a capsule in Aeromonas salmonicida

Aeromonas salmonicida grown in a medium with excess glucose as carbon source produces both capsular and exocellular polysaccharides. The capsular polysaccharide is composed of glucose, mannose, rhamnose, N-acetylmannosamine and mannuronic acid in the molar ratios of approximately 5:3:0.75:2:1. The extracellular polysaccharide is similarly constituted, but in the molar ratios of approximately 4.75:10.5:1.5:2:1. The capsular and exocellular polysaccharides did not cross-react with monoclonal antibodies against the A-layer or the O-antigen lipopolysaccharide.

Effect of culture medium ions on chromate reduction by resting cells of Agrobacterium radiobacter

The influence of some ions in pre-growth culture medium on chromate reduction by resting cells of Agrobacterium radiobacter strain EPS-916 was investigated. The reduction was dependent on the Fe2+ content of the culture medium: the higher the iron content, the lower the reduction rate. The cells showed maximum chromate reduction when pre-grown in the presence of 0.243 μm Mg2+, 20 μm Ca2+ and 3.6 μm Mn2+. Chromate reduction was not affected by the addition of MgCl2, CdCl2, ZnCl2, MnCl2, Na2SO4 (1000 μm), and Na2MoO4 (100 μm) to the activity assays. However, activity was inhibited by the presence of Na2SO4 (10 mm), Na2MoO4 (200 μm) and ferric citrate.