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 have been shown to maintain the natural diversity in vitro and undergo extensive carbonate precipitation.
Several characteristics of these cultivated 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 simulated environmental conditions; and 4) amenability to experimental manipulation (e.g., changing CO2 concentrations, salinity, temperature, diel cycle).
To manipulate the environmental conditions the microbialites are housed in a series of environmental flux chambers. These chambers allow the 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).
