Here's a breakdown:
* Photoautotrophs: These bacteria use light energy to convert carbon dioxide (CO2) into organic compounds, a process called photosynthesis. Think of cyanobacteria (blue-green algae).
* Chemoautotrophs: These bacteria obtain energy from oxidizing inorganic compounds like sulfur, iron, or ammonia. They use this energy to fix carbon, but they don't rely on light.
* Heterotrophs: These bacteria can't fix carbon themselves. Instead, they obtain their energy and carbon by consuming organic compounds produced by other organisms.
Therefore, only a subset of bacteria, the photoautotrophs, use light energy to fix carbon. Many other bacteria use different energy sources and methods for carbon fixation.
