The ASU group found supersaturation of calcium near the surface of the borehole, but undersaturation at the boring front. This finding meant that the mass transfer of calcium could not happen extracellularly, by diffusion in the bored hole, which would require calcium to move against a concentration gradient.
Instead, they discovered that the endolithic cyanobacteria took up calcium from the tips of their boring filaments, directly into their cells. This action promoted the localized dissolution of the calcium-containing carbonate substrate. The calcium was then transported from cell to cell away from the area being quarried, and finally excreted at the entrance of a borehole. The consequences of this transient, but significantly high, concentration of intracellular calcium in the cells remains a question that the Garcia-Pichel laboratory hopes to pursue.
Garcia-Pichel says that he hopes that the newly gained knowledge allows the scientists to explain a variety of geological phenomena and points to new research directions to combat microbial pests of shellfish, such as cultured mussels.
"While it is hard to quantify the losses to the shellfish industry, the impact of endolithic bacteria has been described as a plague by Canadian fisheries," says Garcia-Pichel. "We have identified compounds that abolish the boring activity by inhibiting the enzymatic calcium pumps involved in the process, which may be implemented eventually to protect targets, either by direct application or through genetic engineering of the mussels."
Such studies as these will also help researchers to understand the impact of changes in calcium satu
|Contact: Margaret Coulombe|
Arizona State University