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The capability of reduction of oxidized sulphur compounds (sulphates, sulphites and thiosulphates) by wild strains of sulphate reducing bacteria (SRB) Desulfovibrio desulfuricans DV-5/86 and Desulfotomaculum nigriflcans DT-5/86 was estimated basing on dynamics of hydrogen sulphide liberation. The effectiveness of these processes was correlated with the biocorrosion rate of metallic copper in artificial aqueous media containing above mentioned substrates. It was demonstrated that corrosive aggressiveness of used media with selected sulphur compounds and investigated bacteria strains were the highest in the presence of S2O3-2 ions and the lowest in the system containing SO4-2 ions.
The course of thiosulphate oxidation by selected strains of autotrophic bacteria Thiobacillus thiooxidans and Thiobacillus ferrooxidans as well as mixotrophic bacteria Sulfobacillus sp. and Siderocapsa sp. was analysed. Hexathionate and trithionate were found to be main intermediate compounds in iron-free solutions containing T. ferrooxidans, Sulfobacillus sp. or Siderocapsa sp., whereas tetrathionate was found in systems with T. thiooxidans. Tetrathionates were commonly present in iron-containing solutions inoculated with all tested strains. Chemical and biochemical processes, occurring within tested solutions, are discussed. Ferrous ion concentration > 0.02 g/dm3 was found to have inhibiting effect on the rate of biotic oxidation of thiosulphate.
The study compares growth rates and hydrogenase and APS-reductase activity in crude cell extracts obtained from eight wild strains of dissimilatory sulphate-reducing bacteria of the Desulfovibrio desulfuricans species, growing on sulphate or nitrate as sole energy source. The obtained results indicated that the investigated bacterial strains could utilize nitrate as an alternative terminal electron acceptor. Nitrate respiration abilities differed among the investigated bacterial populations. Some nitrate-utilizing cultures grew more rapidly than sulphate-utilizing ones, whereas other strains gave identical or inconsiderably lower cell density. This was true also when hydrogenase activity was analyzed. This enzyme-specific activity was generally almost directly proportional to the specific growth rate determined for strains cultured on sulphate or nitrate, respectively. The specific activity of APS-reductase indicated a large (10-20-fold) decrease in crude cell extracts obtained from bacteria growing in the presence of nitrate as compared to sulphate-utilizing ones.
The possibility of utilization wastes resulting from mining and burning lignite using the method of microbiological leaching has been presented. It has been found, that high yield (40-80%) of the recovery of metals (Cu, As, Mn, Ga, Be, V, Ti) in the presence of a mixture of Thiobacillus bacteria: T. ferrooxidans and T. thiooxidans, is possible. The effectiveness of metals leaching (basing on titanium extracted) was high both with autochthonous and museum strains of bacteria used.
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