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The removal is discussed of oxidic Fe-phases from industrial silicates by bioleaching. Results are presented which show that small additions of the chelators AQDS or NTA resulted in enhanced Fe (III) reduction or the stimulation of Fe dissolution under non-controlled anaerobic conditions. The bacteria enhanced Fe dissolution indirectly through microbially promoted pH changes and production of organic acids. AQDS stimulated bacterial iron reduction, and Fe2+ concentration in solution was higher than Fe3+. NTA did not stimulate iron reduction but increased bacterial iron dissolution in the form of Fe3+. The concentration of carbon source in the medium was crucial for Fe dissolution and metabolite production. Cheap alternatives such as molasses and food-sugar were used to optimise costs on an industrial scale. The low toxicity of the chelators and bacterial metabolites (pH 4) makes bioleaching an attractive alternative compared with chemical leaching., The removal is discussed of oxidic Fe-phases from industrial silicates by bioleaching. Results are presented which show that small additions of the chelators AQDS or NTA resulted in enhanced Fe (III) reduction or the stimulation of Fe dissolution under non-controlled anaerobic conditions. The bacteria enhanced Fe dissolution indirectly through microbially promoted pH changes and production of organic acids. AQDS stimulated bacterial iron reduction, and Fe2+ concentration in solution was higher than Fe3+. NTA did not stimulate iron reduction but increased bacterial iron dissolution in the form of Fe3+. The concentration of carbon source in the medium was crucial for Fe dissolution and metabolite production. Cheap alternatives such as molasses and food-sugar were used to optimise costs on an industrial scale. The low toxicity of the chelators and bacterial metabolites (pH 4) makes bioleaching an attractive alternative compared with chemical leaching.

Aims: The aim of this study was to investigate extracellular matrix (ECM) and mucin binding of selected bacterial isolates with probiotic features in comparison with commercially used probiotic bacteria. Methods and Results: ECM molecules were immobilized in microtitre plates ( mucin and fetuin) or on the surface of latex beads. Porcine mucin was bound by all 13 probiotic strains tested with important inter-strain differences; however, fetuin binding was similar ( weak) for all 14 strains tested. Strongly positive ( three) binding of bovine fibrinogen was expressed by strains from fermented food ( Lactobacillus rhamnosus GG, L. casei Shirota and L. johnsonii La1) as well as by L. casei L. c., Lactobacillus sp. 2I3 and by L. plantarum LP. The other strains expressed moderate ( 2) or weakly positive ( 1) binding of bovine fibrinogen. Strongly positive ( 3) binding of porcine fibronectin was observed only with two strains; however, all other strains also bound this molecule. Bovine lactoferrin was bound to a higher extent than transferrins. Significance and Impact of the Study: Some animal strains ( at least L. casei L. c. and Lactobacillus sp. 2I3) are comparable with the commercially used strains with respect to their ECM binding ability. As this feature is important for probiotic bacteria to be able to colonize intestine, these strains should be considered for their wider use in fermented feed ( or probiotic preparations) for animals.

Quartz sand containing mineral impurities, from Vysny Petrovec in Slovakia, was biologically leached for 3 months by strains of Bacillus bacteria to determine the reduction of Fe(III)-oxyhydroxides and the effect of particle size on the extent of Fe removal. Bioleaching removed visible Fe-bearing minerals that coated the quartz grains. Elements were dissolved from silicate minerals and poorly crystalline Fe-oxides that sealed siderite nodules were released from intergranular spaces to form a fine-grained fraction whose voltammetry indicated reductive dissolution of Fe3+. Chemical analysis showed a slight increase in Fe2O3 content and a decrease in FeO content. X-ray diffraction analysis showed a loss of Fe-bearing minerals and mica while transmission electron microscopy and energy-dispersive X-ray analysis showed nucleation of fine-grained Fe,Al silicates on the surfaces of bacteria., Quartz sand containing mineral impurities, from Vysny Petrovec in Slovakia, was biologically leached for 3 months by strains of Bacillus bacteria to determine the reduction of Fe(III)-oxyhydroxides and the effect of particle size on the extent of Fe removal. Bioleaching removed visible Fe-bearing minerals that coated the quartz grains. Elements were dissolved from silicate minerals and poorly crystalline Fe-oxides that sealed siderite nodules were released from intergranular spaces to form a fine-grained fraction whose voltammetry indicated reductive dissolution of Fe3+. Chemical analysis showed a slight increase in Fe2O3 content and a decrease in FeO content. X-ray diffraction analysis showed a loss of Fe-bearing minerals and mica while transmission electron microscopy and energy-dispersive X-ray analysis showed nucleation of fine-grained Fe,Al silicates on the surfaces of bacteria.

The ability of Bacillus bacteria to destroy aluminosilicate minerals such as feldspar and quartz suggests that interesting biochemical processes occur in the hypergenic zone. Several kinds of bacteria contribute to the weathering process and accelerate the leaching of elements from rock-forming minerals. Samples from the Horna Prievrana kaolin pit in Slovakia are characterised by a large number of Bacillus and Pseudomonas bacteria, including B. pumilus, B. megaterium, B. cereus and B. mycoides, which coexist together under aerobic and anaerobic conditions in moist environments. Their activity and release of organic compounds into circulating solutions are displayed in the deposit's zonal formation, with kaolin and Fe oxide zones and the remains of graphitic phyllites. Higher extraction of iron, the main contaminant in ceramic and glass raw materials, has been observed under laboratory conditions and suggests a possible new means of processing non-metallic ores., The ability of Bacillus bacteria to destroy aluminosilicate minerals such as feldspar and quartz suggests that interesting biochemical processes occur in the hypergenic zone. Several kinds of bacteria contribute to the weathering process and accelerate the leaching of elements from rock-forming minerals. Samples from the Horna Prievrana kaolin pit in Slovakia are characterised by a large number of Bacillus and Pseudomonas bacteria, including B. pumilus, B. megaterium, B. cereus and B. mycoides, which coexist together under aerobic and anaerobic conditions in moist environments. Their activity and release of organic compounds into circulating solutions are displayed in the deposit's zonal formation, with kaolin and Fe oxide zones and the remains of graphitic phyllites. Higher extraction of iron, the main contaminant in ceramic and glass raw materials, has been observed under laboratory conditions and suggests a possible new means of processing non-metallic ores.

Bioleaching experiments were carried out on iron-contaminated raw materials from Strazov, Cierny and Poproc, Slovakia. A new mineral, weddellite (calcium oxalate dihydrate), was identified in the fine-grained fraction after bioleaching. The formation of weddellite by the destruction of Ca-plagioclase indicated that oxalic acid was one of the metabolites involved in the bioleaching process. Bioleaching resulted in a 35-41% decrease in the Fe content of the Strazov raw material, and subsequent electromagnetic separation reduced the Fe content by up to 69-74%. Bioleaching of the Poproc material, which had a high Fe2O3 content, removed 60% of the Fe, the removal rate increasing to 75% in combination with electromagnetic separation. The removal of Fe resulted in a high-quality, white-coloured product., Bioleaching experiments were carried out on iron-contaminated raw materials from Strazov, Cierny and Poproc, Slovakia. A new mineral, weddellite (calcium oxalate dihydrate), was identified in the fine-grained fraction after bioleaching. The formation of weddellite by the destruction of Ca-plagioclase indicated that oxalic acid was one of the metabolites involved in the bioleaching process. Bioleaching resulted in a 35-41% decrease in the Fe content of the Strazov raw material, and subsequent electromagnetic separation reduced the Fe content by up to 69-74%. Bioleaching of the Poproc material, which had a high Fe2O3 content, removed 60% of the Fe, the removal rate increasing to 75% in combination with electromagnetic separation. The removal of Fe resulted in a high-quality, white-coloured product.

The content of iron oxides in glass of various grades is strictly regulated, but ultra-fine iron particles and clay minerals which coat quartz grains or are impregnated in silicate matrix are difficult to treat using conventional mineral processing methods. Laboratory tests and in situ experiments were carried out to investigate the use of basin water bioleaching with Bacillus spp. followed by dry electromagnetic separation to improve the quality of quartz sands from the Sastin region of Slovakia. The effect of chelators including EDTA, Na2EDTA, Na4EDTA and NTA on the bacterial dissolution of iron impurities was also studied. The rate of iron dissolution varied with environmental conditions and with the addition of chelators and organic feedstock in the form of glucose. Iron removal was higher in the presence of the chelators. Bacterial removal of clay and iron minerals exposed the white surfaces of the quartz grains. In situ treatment of 13 t of quartz sand in a fixed-basin container resulted in the bacterial solubilisation of 22 kg of Fe2O3 after 83 days. The products were suitable for use in the glass industry., The content of iron oxides in glass of various grades is strictly regulated, but ultra-fine iron particles and clay minerals which coat quartz grains or are impregnated in silicate matrix are difficult to treat using conventional mineral processing methods. Laboratory tests and in situ experiments were carried out to investigate the use of basin water bioleaching with Bacillus spp. followed by dry electromagnetic separation to improve the quality of quartz sands from the Sastin region of Slovakia. The effect of chelators including EDTA, Na2EDTA, Na4EDTA and NTA on the bacterial dissolution of iron impurities was also studied. The rate of iron dissolution varied with environmental conditions and with the addition of chelators and organic feedstock in the form of glucose. Iron removal was higher in the presence of the chelators. Bacterial removal of clay and iron minerals exposed the white surfaces of the quartz grains. In situ treatment of 13 t of quartz sand in a fixed-basin container resulted in the bacterial solubilisation of 22 kg of Fe2O3 after 83 days. The products were suitable for use in the glass industry.