Bacterial oxidation of sulfur substances in biotechnology and the environment
Date: 20.4.2006
M. Mandl, Department of Biochemistry, Faculty of Science, Masaryk University, Brno, Czech Republic
Our projects investigate various aspects of biooxidation of inorganic sulfur substances using acidophilic sulfur-oxidizing bacteria.
Spontaneous (bio)oxidation of metal sulfides and elemental sulfur to sulfuric acid results in environmental acidification and toxic metal migration. These processes represent local ecotoxicological problems, especially at abandoned mines. Knowledge of these processes has a broader impact because of analogical biochemical and microbiological principles in biotechnology (biohydrometallurgy - recovery of metals from low-grade ores and concentrates).
We have clarified some steps in arsenopyrite biooxidation mechanism and formation of arsenic ions including their effects on bacteria. Selected enzymes of sulfur metabolism were characterized. Studies on elemental sulfur biooxidation to sulfuric acid contributed to the oxidation mechanism knowledge.
Sulfur limitation and free cell activity were detected as fundamental factors for growth and oxidation kinetics. Iron and arsenic phytotoxicity studies showed general interferences in metal toxicity determination. Proteomic analysis of iron- and sulfur-oxidizing cells of Acidithiobacillus ferrooxidans was investigated to characterize “leaching” bacteria.
Our environmental attention is paid to the study and simulation of processes which proceed spontaneously in sulfide wastes, at present at a Zlaté Hory area. Pyrite and elemental sulfur are the main substrates for our studies from the environmental point of view. Their biooxidation may be described by the following overall equations:
4 FeS2 + 15 O2 + 2 H2O = 2 Fe2(SO4)3 + 2 H2SO4
2 S + 3 O2 + 2 H2O = 2 H2SO4
The environmental problem of acid mine drainages is universal for many sites all over the world. In addition to acidification and toxic metal mobilization, iron released from iron sulfide minerals forms iron precipitates with negative impacts on most of the aquatic organisms.
Knowledge of the process mechanism and factors influencing it provide data which may serve to considerations about acidification regulation under local conditions. Acidithiobacillus ferrooxidans is an useful bacterial model for the above metabolic studies because of its ability to realize all postulated oxidation processes under acid conditions. However, a mixed population of iron- and sulfur-oxidizing bacteria is reported in in situ processes. Another role of sulfur-oxidizing bacteria is related to our current studies on bio-corrosion of concrete materials.
**Grants:**
Czech Science Foundation: 1994 – 2006, 4 projects.
Research intents, Czech Ministry of Education: 1999 – 2011, 2 projects (partial participation).
Fund of the Development of Universities, 2002, 2005, 2 projects.
Czech Ministry of Industry: 2004 – 2007, 2 projects.
Publications from 2000, journals:
Češková P., Mandl M., Hubáčková, J.: Kinetic quantitation of sulfur-oxidizing bacteria adsorbed on sulfur. Biotechnol. Lett. 22, 699-701 (2000).
Bartáková I, Kummerová M., Mandl M., Pospíšil M.: Phytotoxicity of iron in relation to its solubility conditions and the effect of ionic strength. Plant Soil 235, 45-51 (2001).
Bouchal P., Glatz Z., Janiczek O., Mandl M.: Application of capillary zone electrophoresis to study the properties of rhodanese from Acidithiobacillus ferrooxidans. Folia Microbiol. 46, 385-389 (2001).
Češková P., Mandl M., Helánová Š., Kašparovská J.: Kinetic studies on elemental sulfur oxidation by Acidithiobacillus ferrooxidans: Sulfur limitation and activity of free and adsorbed bacteria. Biotechnol. Bioeng. 78, 24-30 (2002).
Češková P., Žák Z., J., Johnson D.B., Janiczek O., Mandl M.: Formation of iodinin by a strain of Acidithiobacillus ferrooxidans grown on elemental sulfur. Folia Microbiol. 47, 78-80 (2002).
Janiczek O., Pokorná B., Zemanová J. Mandl M.: Use of immobilized cytochrome c as a ligand for affinity chromatography of thiosulfate dehydrogenase from Acidithiobacillus ferrooxidans. J. Biotechnol. 117, 293-298 (2005).
Bouchal P., Zdráhal Z., Janiczek O., Helánová Š., Hallberg K.B., Mandl M.: Proteomic and bioinformatic analysis of iron- and sulfur-oxidizing Acidithiobacillus ferrooxidans using immobilized pH gradients and mass spectrometry. Proteomics, in press.
Full papers in books and proceedings:
Mandl M., Češková P., Helánová Š.: Acidophilic bacteria in oxidation of elemental sulfur, in New Trends in Mineral Processing IV, Part I (P. Fečko, Ed.), pp. 43-49. Institute of Environmental Engineering, Faculty of Mining and Geology, Technical University of Ostrava, 2001.
Češková P., Žák Z., Havliš J., Johnson D.B., Janiczek O., Mandl M.: Partial characterisation of a colored metabolite of Acidithiobacillus ferrooxidans grown on elemental sulfur, in Biohydrometallurgy: Fundamentals, Technology and Sustainable Development (V.S.T. Ciminelli and O. Garcia Jr., eds), part A, pp. 363-367. Elsevier, Amsterdam 2001.
Mandl M., Bartáková I., Kummerová M.: Phytotoxicity of pyrite and arsenopyrite biodegradation products, in Environment and Mineral Processing, Part I (P. Fečko, ed.), pp. 193-198. Technical University of Ostrava 2003.
Mandl M., Pokorná B., Helánová Š., Češková P., Janiczek O., Dohnalová R.: Bacterial oxidation of elemental sulfur: changes in metabolic parameters. in Environment and Mineral Processing, Part II (P. Fečko, ed.), pp. 123-125. Technical University of Ostrava, 2005.
