Aerobic anoxygenic phototrophic bacteria (AAPBs) are Alphaproteobacteria and Gammaproteobacteria that are obligate aerobes that capture energy from light by anoxygenic photosynthesis. Anoxygenic photosynthesis is the phototrophic process where light energy is captured and stored as ATP. The production of oxygen is non-existent and, therefore, water is not used as an electron donor. They are widely distributed marine bacteria that may constitute over 10% of the open ocean microbial community. They can be particularly abundant in oligotrophic conditions where they were found to be 24% of the community.[1] Aerobic anoxygenic phototrophic bacteria are photoheterotrophic (phototroph) microbes that exist in a variety of aquatic environments. Most are obligately aerobic, meaning they require oxygen to grow. One aspect of these bacteria is that they, unlike other similar bacteria, are unable to utilize BChl (bacteriochlorophyll) for anaerobic growth. The only photosynthetic pigment that exists in AAPB is BChl-a. Anaerobic phototrophic bacteria, on the contrary, can contain numerous species of photosynthetic pigments like bacteriochlorophyll-a. These bacteria can be isolated using carotenoid presence and medias containing organic compounds. Predation, as well as the availability of phosphorus and light, have been shown to be important factors that influence AAPB growth in their natural environments. AAPBs are thought to play an important role in carbon cycling by relying on organic matter substrates and acting as sinks for dissolved organic carbon. There is still a knowledge gap in research areas regarding the abundance and genetic diversity of AAPB, as well as the environmental variables that regulate these two properties.[2]