M?ssbauer study of dissimilatory reduction of iron contained in glauconite by alkaliphilic bacteria

⁵⁷Fe M?ssbauer investigations of glauconite and new solid phases formed during the process of the bacterial growth in alkaline environment were carried out at room temperature, 78 K and 4.8 K. The magnetically ordered phase formed during bioleaching of glauconite by G. ferrihydriticus in pure culture or in combination with Cl. alkalicellulosi represented as a mixture of off-stoichiometric magnetite and maghemite. In case of combined binary bacterium culture growth the relative content of magnetically ordered phase was more than for the G. ferrihydriticus growth.     

Differential-algebraic equations with a small nonlinear term

In the present paper, we generalize some known results of the theory of differentialalgebraic equations to a more complicated case under the assumption that the nonlinear term is small. We give an asymptotic estimate of the behavior of the solution with respect to the parameter μ.     

Mössbauer study of bacterial iron-reduction processes in natural glauconite and biotite

Interaction between a bacterial monoculture of alkaliphylic G. ferrihydriticus along with binary cultures of G. ferrihydriticus and cellulolytic C. alkalicellulosi and natural biotite and glauconite under alkaliphylic conditions is investigated by means of Mössbauer spectroscopy. Measurements were performed over a range of temperatures from T = 4.8 K to T = 300 K. It was found that a new magnetically ordered phase was formed during culture growth. This new phase was a mixture of nonstoichiometric magnetite and maghemite. The relative amount of the magnetically ordered phase in the monoculture of G. ferrihydriticus when interacting with glauconite is less than in the case of the binary culture. Iron reduction glauconite is also more intense than in biotite.     

Polysaccharide from the leaves ofPhytolacca americana

A polysaccharide has been isolated from the leaves ofPhytolacca americana and has been characterized. It has been established that it contains residues of galactose, arabinose, xylose, and rhamnose, in a ratio of 3:4:1:3 and also D-galacturonic acid (85–90%). The results obtained permit the polysaccharide to be assigned to the class of pectin substances.     

Mössbauer spectroscopy in studying magnetite formed by iron- and sulfate-reducing bacteria

The kinetics of iron mineral formation by thermophilic dissimilatory iron reducing bacteria using Fe(III) amorphous hydroxide and acetate CH₃COO^? as an electron acceptor and donor, respectively, was investigated by Mössbauer spectroscopy. The effects of various physical and chemical conditions and the presence of an inert organic substance on the formation of biogenic minerals were considered. The production of magnetite due to microbial sulfate reduction by hyperthermophilic dissimilatory sulfate-reducing microorganisms was investigated by Mössbauer spectroscopy methods.     

Mössbauer study of iron minerals transformations by <Emphasis Type="Italic">Fuchsiella ferrireducens</Emphasis>

Biogenic transformations of iron-containing minerals synthesized ferrihydrite, magnetite and hydrothermal siderite by anaerobic alkaliphilic bacterium Fuchsiella ferrireducens (strain Z-7101^T) were studied by ⁵⁷Fe Mössbauer spectroscopy. Mössbauer investigations of solid phase samples obtained after microbial transformation were carried out at room temperature and at 82 K. It was found that all tested minerals transformed during bacterial growth. In the presence of synthesized ferrihydrite, added as an electron acceptor, a mixture of large (more than 100 nm) and small (～5 nm) particles of magnetically ordered phase and siderite was formed. Synthesized magnetite that contains both Fe³⁺ and Fe²⁺ forms could serve as electron acceptor as well as an electron donor for F.ferrireducens growth. As a result of its biotransformation, no siderite formation was observed while small particles of magnetite were formed. In the case of the addition of siderite as an electron donor formation of a small amount of a new phase containing Fe²⁺ caused by recrystallization of siderite during bacterial growth was detected.