title: Isolation and biochemical characterization of extracellular polymeric secretions (EPS) from modern soft marine stromatolites (Bahamas) and its inhibitory effect on CaCO3 precipitation.
abstract: Bahamian soft marine stromatolites consist of cyanobacterial biofilms and carbonate sand grains (ooids) embedded in their extracellular polymeric secretions (EPS). EPS were isolated from natural marine stromatolites and the laboratory cultured stromatolite forming cyanobacterium isolate Schizothix sp. Laboratory investigations were conducted to examine biochemical characteristics and the role of EPS in the inhibition of CaCO3 precipitation. EPS consisted of acid polysaccharides and proteins. SDS-PAGE and amino acid analysis suggested that EPS from both soft marine stromatolite and Schizothrix sp. mat contained small proteins (38 kD and 45 kD) enriched in aspartic acid and glutamic acid. Also, immuno blotting suggested that natural EPS contain high molecular weight acid polysaccharide (500 k) which may represent cross-linked products of laboratory cultured Schizothrix sp. acid polysaccharide (300 k). EPS from both soft marine stromatolite and laboratory cultured Schizothrix sp. inhibited CaCO3 precipitation in vitro, as determined using pH drift assays examining pH decrease which occur in response to CaCO3 precipitation. PH drift assays of enzymatically and chemically modified EPS isolated from soft marine stromatolite and laboratory cultured Schizothrix sp. indicated that both uronic acids and protein fractions may be involved in the inhibition of CaCO3 precipitation.
authors.affiliation: Department of Environmental Health Sciences, School of Public Health, University of South Carolina, Columbia 29208, USA. tkawaguchi@sophe.sph.sc.edu
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Kawaguchi
authors.forename: Alan W
authors.initials: AW
authors.lastname: Decho
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000906:Antibodies / Q000276:immunology; D001426:Bacterial Proteins / Q000032:analysis / Q000737:chemistry; D001444:Bahamas; D018441:Biofilms; D001704:Biopolymers / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism*; D002119:Calcium Carbonate / Q000737:chemistry*; D011232:Chemical Precipitation; D000458:Cyanobacteria / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D015151:Immunoblotting; D011134:Polysaccharides / Q000032:analysis / Q000737:chemistry; D012822:Silicon Dioxide; D013997:Time Factors; D014871:Water Microbiology
chemical_list: D000596:Amino Acids; D000906:Antibodies; D001426:Bacterial Proteins; D001704:Biopolymers; D011134:Polysaccharides; D012822:Silicon Dioxide; D002119:Calcium Carbonate