Prokaryotic organisms need to have a high level of metabolic flexibility to survive in competitive environments. This is due to large pressures on nutrients and space for the organism to grow in. These environments also tend to have variable environmental conditions, including temperature and oxygen concentration.
Having a high level of flexibility allows a prokaryote to survive in these variable environments, improving its survival chances.
For example, Campylobacter, a common form of food poisoning, has metabolic flexibility. Found in poultry gastrointestinal tracts, it can be transferred to meat products during butchery, and cross-contamination is easy in high-speed meat processing plants. As the meat will be stored at fridge temperatures (2-5C), the bacteria need to be able to maintain metabolic functions before it enters a host. If poor cooking practices are then used (such as not defrosting correctly, or not reaching a proper core temperature), the Campylobacter are able to enter the host, colonising the GI tract, and causing food poisoning symptoms. The ability of the bacteria to survive across a 60C temperature range demonstrates the importance of flexibility to the bacteria’s survival.