Iron And Sulfur Oxidizing Bacteria 1g5e6m

IRON AND SULFUR OXIDIZING BACTERIA By : Nadyatul Hanifah B1K014006

Sulfur- and Iron-Oxidizing Bacteria -

Chemolithoautotrophs, obtain energy from the oxidation of inorganic compounds and carbon from the fixation of carbon dioxide Aerobic, Sulfides are converted to sulfate (SO4-2) sulfate is assimilated by plants and microbes Two broad classes • Neutrophiles

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• Acidophiles Some acidophiles able to use ferrous iron (Fe2+)

Sulfur Oxidizing bacteria (cont.) – Thiobacillus and close relatives are best studied • Rod-shaped • Sulfur compounds most commonly used as electron donors are H2S, So, S2O32-; generates sulfuric acid – Achromatium • Common in freshwater sediments • Spherical cells • Pylogenetically related to purple bacteria Chromatium

Nonfilamentous Sulfur Chemolithotrophs

carboxyso mes Halothiobacillus neapolitanus

Elemental sulfur Calcium carbonate (CaCO3) Achromatiu m sp.

Sulfur Oxidizing bacteria (cont.) – Beggiatoa • Filamentous, gliding bacteria • Found in habitats rich in H2S – e.g., sulfur springs, decaying seaweed beds, mud layers of lakes, sewage polluted waters, and hydrothermal vents • Most grow mixotrophically – is an organism that can use a mix of different sources of energy and carbon, instead of having a single trophic mode on the continuum from complete autotrophy at one end to heterotrophy at the other. – with reduced sulfur compounds as electron donors – and organic compounds as carbon sources (∵ lack Calvin cycle enzymes)

Filamentous Sulfur-Oxidizing Bacteria

Beggiatoa sp.

Sulfur Oxidizing bacteria (cont.) – Thioploca • Large, filamentous sulfur-oxidizing bacteria that form cell bundles surrounded by a common sheath • Thick mats found on ocean floor off Chile and Peru • Couple anoxic oxidation of H2S with reduction of NO3- to NH4+

– Thiothrix • Filamentous sulfur-oxidizing bacteria in which filaments group together at their ends by a holdfast to form cellular arrangements called rosettes • Obligate aerobic mixotrophs, in order to growth and maintenance, an organism must utilize both heterotrophic and autotrophic means.

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Cells of a Large Marine Thioploca Species Thiothrix

Physiological Characteristics of Sulfur Oxidizers

Bioleaching • •

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Iron and sulfur oxidizing bacteria are important in bioleaching process For example Acidithiobacillus ferrooxidans (formerly known as Thiobacillus ferrooxidans) and Acidithiobacillus thiooxidans (formerly known as Thiobacillus thiooxidans) Bioleaching is the extraction of metals from their ores through the use of living organisms As a general principle, Fe3+ ions are used to oxidize the ore. This step is entirely independent of microbes. The role of the bacteria is the further oxidation of the ore, but also the regeneration of the chemical oxidant Fe3+ from Fe2+

The microbial oxidation process occurs at the cell membrane of the bacteria. The electrons into the cells and are used in biochemical processes to produce energy for the bacteria while reducing oxygen to water. The critical reaction is the oxidation of sulfide by ferric iron. The main role of the bacterial step is the regeneration of this reactant