Abstract:Algae and bacteria are inseparable in the ocean and have sophisticated interactions with each other, including mutualism, commensalism, antagonism, competition and parasitism. They are both major players in regulating the structure and function of marine ecosystem. Around a single algae cell, there usually exists a special microenvironment called “phycosphere” inhabited by specific microbial communities. The phycosphere is the main location for the interactions between algae and bacteria. The formation of specific microbial assembly within algal phycosphere has certain regularity. In natural ecosystem, the algae-bacteria interactions affect the dynamic process of the red tide and play important roles in water quality restoration. Moreover, algae and bacteria are the major drivers for marine carbon fixation and sequestration, their interactions have important impacts on marine carbon cycling. In view of the current research status of marine algae-bacteria interactions, several research prospects are discussed, for example, the role of viruses in regulating the relationship between algae and bacteria is poorly understood and awaiting a deep study.