for nitrogenase (leading to overestimates of nitrogenase by ARA). Bottle or chamber-based assays may produce negative impacts on microbial systems as a result of containment or disruption of the microenvironment through handling, leading to underestimation of nitrogenase. Despite these weaknesses, such assays are very useful in assessing relative rates or temporal patterns in nitrogenase activity. See also Nitrogen fixation Abiological nitrogen fixation References Further reading External links EC 1.18.6 Iron–sulfur proteins Nitrogen cycle Molybdenum enzymes