Photosynthetic autotrophic bacteria use sunlight to make their own food. Photosynthetic autotrophs synthesize organic compounds. 
Chemosynthetic autotrophic bacteria make use of chemical to prepare their food. These bacteria obtain energy from inorganic compounds.
1 2 1
Plants get energy from the sun through a process called photosynthesis; this process supports nearly all life on earth. But photosynthesis is not the only method that living organisms use to create energy. Some microorganisms derive energy from chemical reactions that don’t require light and use this energy to assemble organic molecules through a process called chemosynthesis.Chemosynthesis, akin to photosynthesis, is a process certain organisms use to produce energy, but without the utilization of sunlight. The hydrogen they use comes from hydrogen sulfite, whereas the nitrogen comes from ammonia or nitrates. The energy comes from the oxidization (burning) of chemicals which seep up from the Earth’s crust.Once it’s produced ATP, the bacterium can use the energy it’s stored in ATP to turn inorganic compounds like CO2 and hydrogen sulfide into organic compounds like glucose. This final series of reactions is just chemosynthesis. The organisms that use chemosynthesis, all bacteria, manufacture carbohydrates and other organic molecules from the oxidization of sulfates or ammonia.