Which of the following statements best describes the nitrifying bacteria Nitrosomonas and Nitrobacter?

The statement is correct because Nitrosomonas and Nitrobacter are indeed slow-growing autotrophic bacteria. They play a crucial role in the nitrogen cycle, specifically in the process of nitrification. Nitrosomonas is responsible for oxidizing ammonia (NH3) to nitrite (NO2-), while Nitrobacter further oxidizes nitrite to nitrate (NO3-).

These bacteria utilize inorganic compounds as their source of energy, which is essential for their metabolism. Being autotrophic means they can produce their own food using inorganic substances, utilizing the energy derived from the oxidation of ammonia and nitrite instead of relying on organic compounds.

The other options describe characteristics that do not apply to these bacteria, such as the need for excessive amounts of dissolved oxygen or being rapid-growing anaerobic bacteria, which do not accurately represent how Nitrosomonas and Nitrobacter function in their natural environments. This understanding is critical in wastewater treatment processes, as proper management of nitrogen levels is vital for maintaining system efficiency and health.