| STUDY |
Graduate student Thomas D. Perry IV of Harvard University's division of engineering and applied sciences is studying bacterially produced polymers that promote degradation of limestone made of calcite. Perry, his adviser Ralph Mitchell, and professor Scot T. Martin are using atomic force microscopy to image polymer-promoted dissolution of a calcite surface while measuring the rate of dissolution. -------------------------------------------------------------------------------- Bacteria and other microbes impact just about every geochemical process that one can think of. -------------------------------------------------------------------------------- THE FIRST POLYMER they have investigated--alginic acid, a linear copolymer consisting primarily of -1,4-linked D-mannuronic acid and -1,4-linked L-glucuronic acid--is produced by many kinds of microorganisms. Even at concentrations as low as 0.1%, alginic acid dramatically increases calcite dissolution over a wide pH range, Perry reported at the symposium. He suggested that the polymer does so by preferentially binding to and chelating calcium ions found in exposed "pits" in the calcite surface. Perry and colleagues are now investigating the effects of other polymers produced by microorganisms that live on the limestone blocks of the ruins of the ancient Mayan city of Ek Balam, located near Playa del Carmen in Mexico. He hopes the work may lead to methods to prevent microbe-mediated deterioration of these and other irreplaceable ancient structures. |
| UPDATE | 10.03 |
| AUTHOR | Graduate student Thomas D. Perry IV of Harvard University's division of engineering and applied sciences is studying bacterially produced polymers that promote degradation of limestone made of calcite. Perry, his adviser Ralph Mitchell, and professor Scot T. Martin |
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