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Microbially influenced formation of Mg‐calcite and Ca‐dolomite in the presence of exopolymeric substances produced by sulphate‐reducing bacteria
Author(s) -
Bontognali Tomaso R. R.,
McKenzie Judith A.,
Warthmann Rolf J.,
Vasconcelos Crisogono
Publication year - 2014
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1111/ter.12072
Subject(s) - dolomite , calcite , mineralization (soil science) , carbonate , bacteria , environmental chemistry , incubation , sulfate reducing bacteria , mineralogy , geology , chemistry , biomineralization , carbonate minerals , biochemistry , organic chemistry , nitrogen , paleontology
Some species of sulphate‐reducing bacteria ( SRB ) are known to mediate the formation of dolomite and Mg‐calcite. However, their exact role in the mineralization process remains elusive. Here, we present the result of a laboratory experiment that was designed to test whether formation of carbonate minerals by SRB can occur in the absence of living cells, through passive mineralization of their exopolymeric substances ( EPS ). SRB capable of mediating dolomite were cultivated in the laboratory, allowing them to secrete EPS . Microbial activity within the cultures was subsequently inhibited with antibiotics. Only after this step, Ca 2+ and Mg 2+ were added to the solution and carbonate minerals could form. Mg‐calcite and disordered Ca‐dolomite precipitated in association with EPS . The mol.% of Mg 2+ in the crystals increased with longer incubation times. This result demonstrates that organic compounds produced by SRB can mediate the formation of Ca‐Mg carbonates in the absence of an active metabolism.