Sulphate Reducing Bacteria for the Treatment of Heavy Metals Contaminated Waters in Permeable Reactive Barriers

The aim of the work was the comparison between a selected reactive mixture containing organic matter for SRB and other electron donors, such as ethanol and polysaccharides. The comparison was performed in order to select the best operating conditions in terms of organic sources for SRB. A continuously operating fixed-bed column was filled with a batch-optimised solid reactive mixture (6% leaves, 9% compost, 3% zero valent iron, 30% silica sand, 30% perlite, 22% limestone) and inoculated by SRB. At steady state 50±10% sulphate abatement was reached and metals were totally removed. Batch tests with ethanol showed the ability of SRB to grow on this substrate efficiently. Experimentation using ethanol was performed using two different column reactors filled with perlite, one inoculated by SRB and the other used as blank. Sulphate abatements of the inoculated column were 70±10% against 10±5% of the blank column. Preliminary batch tests with polysaccharides showed the ability of bacteria to grow on these substrates.

Immunoaffinity Column as Sample Cleanup Method for Determination of the Beta-Adrenergic Agonist Ractopamine and Its Metabolites

A monoclonal antibody-based immunoaffinity column (RAC-IAC) was developed as a cleanup method for the determination of ractopamine and ractopamine glucuronides. [14C]Ractopamine (5 μg) and [14C]ractopamine glucuronides (5 μg) were fortified into 10 mL cattle urine, and loaded onto an RAC-IAC (5 mg IgG/mL) column. The column was washed and the bound analytes were eluted. In the initial loading and washing, 22% of the radioactivity was washed off and the subsequent elution step recovered 78%. A blank column prepared from nonspecific IgG retained <10% of the radioactivity. The RAC-IACs were damaged by high methanol concentrations, preventing reuse. Elution of the analytes with 50mM glycine buffer, pH 2.8, prevented damage, and the columns could be reused at least 20 times with no change in performance. They were stored >3 months in phosphate- buffered saline with 0.02% sodium azide at 4°C. The method was used with fortified cattle muscle, liver, and kidney samples with recoveries of 82.1 ± 7.6, 87.8 ± 1.9, and 92.5 ± 0.4%, respectively (n = 3). Similar studies with sheep muscle, liver, and kidney samples gave recoveries of 91.8 ± 0.2, 91.7 ± 0.3, and 92.3 ± 0.3, respectively ( n = 3). Liver and kidney samples were diluted to prevent column plugging, but all of the eluants were suitable for liquid chromatography analysis. This IAC is a selective, efficient, and economical cleanup method in a variety of matrixes for ractopamine determination.

Possible pitfalls in the identification of glycophorin-binding proteins of Plasmodium falciparum.

Plasmodium falciparum proteins that bind to the putative erythrocyte receptor (glycophorin) have been identified in several laboratories by their ability to bind to glycophorin immobilized on aminoethyl-BioGel (AE-BioGel). We here report that several parasite proteins bind to AE-BioGel in the absence of coupled glycophorin. Binding is apparently due to the strong ion-exchange properties of the matrix, and is sensitive to ionic conditions such as the degree of equilibration of the matrix and the pH. The parasite proteins that bind to the blank column under appropriate conditions include proteins with the serological activities of S-antigen and Ag 23, which also bind to glycophorin-coupled AE-BioGel. In the light of these results, the glycophorin-binding specificity of these and other proteins reported to bind to glycophorin-coupled AE-BioGel will have to be reevaluated, preferably using a different support matrix.