Biogeo chemical cyle...(Sulfur cycle).pptx

Sulfur is one of the most abundant elements on the earth.
Sulfur is a yellow, brittle, tasteless, odourless non-metal.
Sulfur is present in all kinds of Proteins.
Plants directly absorb Sulfur-containing Amino acids such as Methionine, Cystine and Cysteine

1. Sulfur cycle B. LOKESHWARI II M. Sc MICROBIOLOGY SACRED HEART COLLEGE (AUTONOMOUS) TIRUPATTUR.

2. INTRODUCTION One of the most abundant elements on the earth. Sulfur is a yellow, brittle, tasteless, odourless non-metal. Present in all kinds of Proteins. Plants directly absorb Sulfur-containing Amino acids such as Methionine, Cystine and Cysteine. Sulfur is released into the atmosphere by the Volcanic activities Burning of fossil fuels Decomposition of Organic molecules

3. On land, Sulphur is stored in underground rocks and minerals. It is released by Precipitation, Weathering of rocks and Geothermal vents. Describes the movement of Sulfur through the atmosphere, mineral forms, and through living things. Microbial transformations of Sulfur are even more complex than those of Nitrogen because Large number of Oxidation states of Sulfur Several transformations of Sulfur also occur spontaneously ( abiotically )

4. STEPS INVOLVED – 4 STEPS

5. 1. SULFUR DISSIMILATION (SULFATES [SO42–] TO HYDROGEN SULPHIDE [H2S]) Protein degradation in Dead materials releases Amino acids that contain Sulfur. Sulfur released from Amino acids forms Sulfate (SO42–) is converted to its most reduced form, Hydrogen sulfide (H2S) by a process called Dissimilation. Desulfovibrio sp., Desulfobacter sp . and Archaeoglobus sp . are involved .

6. 2. OXIDATION OF HYDROGEN SULPHIDE (H2S) TO ELEMENTAL SULFUR. Hydrogen Sulphide (H2S) is oxidized to Elemental sulfur (S0) under various conditions. Oxidation of Hydrogen Sulphide (H2S) to Elemental sulfur (S0) was carried out under both Aerobic and anaerobic conditions. Aerobic condition - Thiobacillus sp., Beggiatoa sp., Thiothrix sp . and Aerobic anoxygenic phototrophs Anaerobic condition - Photolithotrophic sulfur oxidizers such as Chromatium sp . and Chlorobium sp.

7. 3 . OXIDATION OF ELEMENTAL SULFUR TO SULFATE (SO42–) Oxidation of Elemental sulfur (S0) to Sulfate (SO42–) was carried out under Anaerobic condition by Alteromonas sp., Clostridium sp., Desulfovibrio sp. and Desulfotomaculum sp. This process is a Two steps Anaerobic process ;

8. 4 . RETURN OF PHOSPHOROUS BACK TO ECOSYSTEM THROUGH DECOMPOSITION Sulfates are reduced to Hydrogen Sulphide (H2S) anaerobically by Desulfovibrio desulfuricans , Desulfomonas sp. and Desulfotomaculum sp. This reduction process occurs in two steps ;

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