Winogradsky column day 7

Winogradsky column
day 7

The lower part of the sediment has changed color to black. I suppose this is due to the development of metal sulfides from metals and minerals in the mud. Now two types of microorganisms flourish, namely species of the genus Clostridium and so called sulfate-reducing bacteria, e.g. Desulfovibrio. The main reactions of the symbiosis between these microorganisms are shown bellow.

Clostridium

(C6H10O5)n	→	C2H6O	+	–COOH
cellulose (toilet paper)		ethanol		organic acids

Sulfate-reducing bacteria

C2H6O

+

CaSO4

→

H2S

+

CH4

+

CaO

+

CO2

+

H2

ethanol

gypsum

hydrogen sulfide

methane

calcium oxide

carbon dioxide

hydrogen

References

• http://www.personal.psu.edu/faculty/j/e/jel5/biofilms/winogradsky.html
• http://www.biology.ed.ac.uk/archive/jdeacon/microbes/winograd.htm
• http://www.mbio.ncsu.edu/MB452/Winogradsky_columns/wc.html
• http://ecosystems.mbl.edu/SES/MicrobialMethods/MicrobialBiogeochemistry2010.pdf
• Samia Azabou, Tahar Mechichi, Sami Sayadi.Sulfatereduction from phosphogypsum using a mixed culture of sulfate-reducing bacteria. Laboratoire des Bio-procédés, Centre de Biotechnologie de Sfax BP “K”, 3038 Sfax, Tunisia