Artificial Microbialites
To examine the underlying genetic mechanisms of microbialite biomineralization, laboratory cultivated microbialites are used to model the natural environment. Cultivated microbialites grown under simulated environmental conditions and are referred to as artificial microbialites. These artificial microbialites have been shown to maintain the natural diversity in vitro and undergo extensive carbonate precipitation (Havemann and Foster, 2008 (Download paper).
Several characteristics of these artificial microbialites make them idea models to examine the genetic mechanisms of carbonate biomineralization, including:
1) rapid growth and accretion under simulated lab conditions; 2) similar species diversity compared to natural field-collected stromatolites; 3) continued production of lithified organosedimentary structures under artificial seawater conditions; and 4) amenability to experimental manipulation (e.g., changing CO2 concentrations, salinity, temperature, diel cycle).
Environmental manipulations
To manipulate the environmental conditions the artificial microbialites are housed in four environmental flux chambers. These chambers allow artificial microbialites to be exposed to differential CO2, pH, and saline conditions. All of these variables are thought to be essential for carbonate precipitation (e.g. Dupraz and Visscher, 2005; Dupraz et al., 2009). An infrared gas analyzer (LI-COR 6252)
monitors changes in CO2 flux within the chambers. Measurements are automatically recorded every 5 minutes and CO2 concentrations and adjusted using a Command Monitoring Data System (Opto22; Temecula, CA).
