title: A proton buffering role for silica in diatoms.
abstract: For 40 million years, diatoms have dominated the reverse weathering of silica on Earth. These photosynthetic protists take up dissolved silicic acid from the water and precipitate opaline silica to form their cell wall. We show that the biosilica of diatoms is an effective pH buffer, enabling the enzymatic conversion of bicarbonate to CO2, an important step in inorganic carbon acquisition by these organisms. Because diatoms are responsible for one-quarter of global primary production and for a large fraction of the carbon exported to the deep sea, the global cycles of Si and C may be linked mechanistically.
authors.affiliation: Department of Geosciences, Guyot Hall, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Allen J
authors.initials: AJ
authors.lastname: Milligan
authors.forename: François M M
authors.initials: FM
authors.lastname: Morel
mesh_terms: D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D002021:Buffers; D002245:Carbon Dioxide / Q000378:metabolism; D024402:Carbonic Anhydrase II / Q000378:metabolism; D002256:Carbonic Anhydrases / Q000302:isolation & purification / Q000378:metabolism*; D002384:Catalysis; D002417:Cattle; D002473:Cell Wall; D011232:Chemical Precipitation; D002696:Chlamydomonas / Q000378:metabolism; D017377:Diatoms / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry; D011522:Protons; D012623:Seawater; D012822:Silicon Dioxide / Q000378:metabolism*
chemical_list: D001639:Bicarbonates; D002021:Buffers; D011522:Protons; D002245:Carbon Dioxide; D012822:Silicon Dioxide; D024402:Carbonic Anhydrase II; D002256:Carbonic Anhydrases