The type of medium in the agar plates is also important. Chromagar Candida is a differential medium that is used to identify different "Candida" species. When grown on this medium, "C. albicans" is light green, "C. tropicalis" is steel blue with purple around the edges, and "C. krusei" is rose pink with white around the edges. However, using a different medium, "C. tropicalis" has maroon colonies. The color of the medium itself can also be changed using microbes. In TCBS agar, Bromthymol Blue and Thymol Blue turn yellow when the pH decreases, such as when bacteria consume sucrose. In this way, the background color of the medium can be changed from dark green to light yellow.