Adding microorganisms to the environment to speed up biodegradation in the case of soil or water contamination. For example, oil spill remediation often involves using the enzymatic action of indigenous hydrocarbons–degrading microbial populations and modifying environmental factors to achieve enhanced rates of oil spill biodegradation. Seeding involves the introduction of exogenous microorganisms into the natural environment to increase the rate and extent of biodegradation of pollutants. This is because the indigenous microbial population may not be capable of degrading the wide range of potential substrates present in a complex mixture like petroleum.