Microbial ecology covers sub-disciplines of both microbiology and ecology. To put it briefly, it is the study of the roles and relationships that microorganisms (predominantly bacteria and fungi) have with the environment and other organisms within the environment. There is much overlap in the topic areas, and often research covers several different sub-disciplines simultaneously. Major topic areas within microbial ecology are ecology, microbiology, soil science, agriculture, bioremediation, environmental science, biogeography, biogeochemistry, oceanography, restoration ecology, and dentistry/biofilm biology. Researchers and research programs cover a broad spectrum of topics; for example, molecular researchers who are interested in the metabolic processes and physiology involved in the bioremediation process. Ecologists can also use bacteria for addressing basic questions about ecological theories that can better be answered using bacteria as model populations or communities than could be answered with larger organisms and their subsequent longer generation times.