Aquatic Sciences Meeting, Albuquerque 2001
| SS43 Biogeochemical Processes in Stromatolites: A 3 b.y.old ecosystem (Spatial and Temporal Connections) |
| Date: Monday, February 12, 2001, Time: 4:00:00 PM |
| Location: Cimarron |
| Kawaguchi, T, , Dept of Env Health Sciences, University of South Carolina, Columbia, SC, USA, tkawaguchi@sophe.sph.sc.edu |
| Decho, A, W, Dept of Env Health Sciences, University of South Carolina, Columbia, SC, USA, adecho@sph.sc.edu |
| THE ROLE OF EXTRACELLULAR POLYMERIC SUBSTANCES ON CaCO3 PRECIPITATION IN MARINE STROMATOLITES. |
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| Bahamian stromatolites produce a variety of forms of calcium carbonate precipitates. Many of these occur in close association with cyanobacterial biofilms and their extracellular polymeric substances (EPS). EDTA soluble fractions of EPS (s-EPS)were isolated from the marine stromatolites. Laboratory studies were conducted to examine the role of s-EPS, in precipitation events. S-EPS inhibited CaCO3 precipitation in vitro, as determined using pH drift assays recording pH decreases that occur in response to CaCO3 precipitation. Also, CaCO3 induction experiment demonstrated that s-EPS attached on the solid surface induced CaCO3 crystal formation in vitro. Although our results are preliminary, our data suggested that s-EPS may inhibit CaCO3 precipitation when in solution, and when it attached to the insoluble substrate may act as a nucleation site of CaCO3 precipitation. Therefore, s-EPS may have a more direct role in CaCO3 precipitation in the marine stromatolites than previously thought. |
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