Citrobacter freundii is a facultative anaerobic bacterium with significant roles in bioremediation, agriculture, and wastewater treatment. Known for its ability to reduce nitrates and detoxify heavy metals such as cadmium, lead, and chromium, it is widely used in mitigating environmental pollution.

In agriculture, C. freundii contributes to nutrient cycling by breaking down organic matter, enhancing soil fertility. It also aids in wastewater treatment by degrading complex organic compounds, reducing chemical oxygen demand (COD), and improving water quality. With its metabolic flexibility and environmental resilience, C. freundii is a valuable tool in sustainable environmental management and industrial processes..