Microalga Growth-Promoting Bacteria (MGPB): A formal term proposed for beneficial bacteria involved in microalgal–bacterial interactions

Studies on the microalgal–bacterial interactions have highlighted the potential role of bacteria in optimizing microalgal biorefineries for the integrated production of metabolites and biomass, biodiesel, and wastewater treatment. Although the bacterial mechanisms responsible for the positive effects on microalgal growth and metabolism have been defined in many instances, there is a lack of a unified term to describe these beneficial bacteria. In this review, we provide arguments for the convenience of using a single term, Microalga Growth Promoting Bacteria (MGPB), to define non-specific bacteria that promote microalgal growth and/or affect their metabolism, especially for biotechnological purposes. We describe the strategies that beneficial bacteria use in several microalgal cultivation systems and the variety of terms used over time to refer to these kinds of bacteria. We also describe the bacterial mechanisms that have been studied affecting the microalgae, propose specific requirements that a bacterial species should meet to be considered an MGPB, and highlight the perspectives for its use.