A typical soil sample has billions of microorganisms due to its moist, nutrient rich composition. Common soilinhabiting bacteria include: Bacillus, Streptomyces, Pseudomonas, Micrococcus, coliforms (indicators of fecal contaminants), lactic acid bacteria, and Clostridium. Various fungi (molds) are also frequently found in soil samples. These organisms play a critical role in the different natural biogeochemical cycles. Bacteria meet their nutrient needs by metabolizing organic matter (decomposing plants and animals) in soil, thereby oxidizing and reducing the elements in the organic matter and returning those elements to the environment. In this experiment, you will examine the diversity of soil microorganisms by culture bacteria from a soil sample and performing some microbiological tests to attempt to identify the microbes.
What is the source of the bacterial colonies in the heated samples?