Here's why:

* Aerobic: This means the bacterium uses oxygen for respiration.

* Chemosynthetic: This means the bacterium obtains energy from the oxidation of inorganic compounds, not sunlight like photosynthetic organisms.

Example:

* Nitrifying bacteria: These bacteria are aerobic and use the oxidation of ammonia (NH3) to nitrite (NO2-) and then nitrite to nitrate (NO3-) as their energy source.

Key Point: The ability to use oxygen for respiration (aerobic) and obtain energy from inorganic compounds (chemosynthesis) are not mutually exclusive.

Therefore, many aerobic bacteria can be chemosynthetic, playing important roles in various biogeochemical cycles.