Petroleum degradation is the process by which microorganisms break down petroleum compounds into simpler compounds, typically as a means of obtaining energy and nutrients. Petroleum is a complex mixture of hydrocarbons, consisting of various compounds such as alkanes, aromatics, and polycyclic aromatic hydrocarbons (PAHs), and is a major environmental pollutant.

Microbial degradation of petroleum can occur naturally in the environment or can be induced through bioremediation, a process in which microorganisms are used to degrade pollutants. Many different types of microorganisms, including bacteria and fungi, are capable of degrading petroleum compounds, with some being more efficient at degrading certain types of compounds than others.

The process of petroleum degradation typically involves three stages: (1) the uptake of petroleum compounds by microorganisms, (2) the metabolism of these compounds, and (3) the production of simpler compounds and carbon dioxide as byproducts. Microorganisms use various mechanisms to break down petroleum compounds, including the use of enzymes, oxidation-reduction reactions, and the production of surfactants to increase the solubility of hydrophobic compounds.

Petroleum degradation can occur under aerobic or anaerobic conditions, with the efficiency of degradation depending on factors such as the type of microorganism present, the availability of nutrients and oxygen, and the environmental conditions. Bioremediation techniques that harness the power of microbial degradation can be an effective way of cleaning up petroleum-contaminated environments, though the success of these methods depends on many factors, including the size and complexity of the contaminated area.