Autotrophic bacteria include cyanobacteria, green sulfur bacteria, purple bacteria, halophiles and methanogens. These bacteria, along with several types of plants and fungi, have the ability to produce their own food through photosynthesis. They use light, water and carbon dioxide or other chemicals to transform sunlight into glucose — a type of sugar then used for energy.
Cyanobacteria, also called blue-green algae, are among the most common types of autotrophic bacteria. These organisms are not related to other types of algae but nonetheless also live in aquatic environments, such as lakes and oceans, and produce food using sunlight. Cyanobacteria, like plants, contain cellular structures called chloroplasts, which allow them to perform photosynthesis. Cyanobacteria are among the oldest living organisms on earth with fossil records dating back over 3.5 billion years. While cyanobacteria create energy using photosynthesis, others rely on chemosynthesis to make their food. According to National Geographic, most of the autotrophic bacteria that use chemosynthesis live deep below the surface of the sea and make their homes in cold seeps. Cold seeps are essentially underwater caves that contain a mixture of chemicals, primarily hydrogen sulfide and methane, that these bacteria require for chemosynthesis. Most autotrophic bacteria live in cooler regions with the exception of green sulfur bacteria, which thrive in hot springs and warm waters.