Final answer:
Autotrophic bacteria can produce their own food through photosynthesis, while heterotrophic bacteria obtain food by consuming other organisms or organic compounds.
Step-by-step explanation:
Autotrophic bacteria are able to create their own food source without consuming other organisms. They achieve this by using photosynthesis, a process that converts light energy into chemical energy. An example of autotrophic bacteria is cyanobacteria, which plays an important role in aquatic food webs. On the other hand, heterotrophic bacteria obtain their food by consuming other organisms or organic compounds. Some species of bacteria, such as alpha proteobacteria, can exhibit both autotrophic and heterotrophic characteristics depending on their environment and nutritional needs.