Biological Sciences / 6. Microbiology

Ph D in biology Berseneva O.A

Irkutsk State University, Russia

Innovations and new resource-saving technologies in the processing of sulphide ore

Currently, in connection with one of the global environmental problems of modernity (mineral depletion of natural resources) especially important is search and development of resource-saving technologies. One of the approaches to solving problem of depletion of mineral raw materials is the use bioleaching based оn the extraction of chemicals compounds from multicomponent microorganisms through their dissolution in aqueous medium with bacteria or their metabolites [1,3]. Thanks to the technology of bacterial leaching it is possible extraction from ores, mining waste and metallurgical production of valuable components (different metals) [2,4,5].

Useful for bacterial leaching of mineral products has properties of about 30 bacterial cultures [2,7,8,9,10]. However, the main actively applied in practice, bacterial leaching of metals is the kind thiobacteria named Thiobacillus ferrooxidans. [2,7]. This type of bacteria is capable of oxidizing practically all metal sulfides [2,7].

The aim of this study was isolation of autochthonous acidophilic chemolithotrophic microorganisms associations for further possible application of these associations in the technology of bacterial leaching technology of sulfide ores from waste.

Sources for the isolation of microorganisms were coal dumps in the area is actively developing coal deposits "Cheremhovsky" (Irkutsk region, Cheremhovo).

Getting funded cultural association chemolithotrophic autochthonous microorganisms from the oxidized ore coal mine "Cheremhovsky" was carried out in mesophilic conditions (30 ± 20 ° C) with a solution of mineral salts of Silverman-Lyundgrena and Waxman.

For the cultivation of microorganisms of 1 g of ore was thoroughly stirred in 100 ml distilled water and added to 1 ml of suspension in each flask with selection medium. As a control we used sterile selection medium without sample.

Determination of the amount of iron (II) was carried out photometrically. For this took 1 ml of culture liquid with cells are placed in a test tube was added 2 ml of 10% sulfosalicylic acid; 0.1 ml of 2N sulfuric acid, stirred and the solution volume was adjusted to 10 ml with distilled water. The absorbance of the mixture was measured with a spectrophotometer NanoPhotometer P 330, Implen at 510 nm. cuvette width of 10 mm. Determination led by the values of the standard curve, which was built in the same conditions, using a sample of iron-ammonium alum with 0.1-1 mg / ml iron (II) solution. The duration of the process was 30 days [6].

In the process of accumulation of microbial cultures, within a month of cultivation of the investigated samples of coal ore mine "Cheremhovsky " highlighted various representatives of microbial associations.

The study microbial associations is presented species A. ferroxidans (motile, gram-negative, single and in chains asporogenous rods, aerobic, moderate thermophiles (upper temperature limit of 40⁰C ), pH tolerance range of 2.0 to 4.0 ) and A. thiooxidans ( mobile, gram-negative, small nonsporogenous sticks, aerobic, mesophiles (optimum temperature of 30 - 37⁰C) , the optimum development pH 2,0-4,0.

Studying the dynamics of substrate oxidation revealed that increasing the concentration of iron in solution starting from the 4 th to 15 th day of cultivation, and increases from an initial concentration of 1 g/l at 15 day in medium Silverman 7 times, and in medium Waksman 5 times от day 8 day of cultivation.

The results of these studies have shown that the highest oxidized ability found in medium Silverman-Lundgrena, but the allocation of iron affects more time than medium Waksman.

Therefore, we assume that data obtained to determine the living condition of the chemolithotrophic microbial associations and intensity of the oxidation of iron can be used to extraction of iron from sulfide ores.

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