Toward the Enhancement of Microalgal Metabolite Production through Microalgae-Bacteria Consortia

Simple Summary Microalgae are photosynthetic microorganisms with high biotechnological potential. However, the sustainable production of high-value products such as lipids, proteins, carbohydrates, and pigments undergoes important economic challenges. In this review, we describe the mutualistic association between microalgae and bacteria and the positive effects of artificial consortia on microalgal metabolites' production. We highlighted the potential role of growth-promoting bacteria in optimizing microalgal biorefineries for the integrated production of these valuable products. Besides making a significant enhancement to microalgal metabolite production, the bacterium partner might assist in the biorefinery process's key stages, such as biomass harvesting and CO2 fixation. Engineered mutualistic consortia of microalgae and bacteria may be a means of assembling a novel combination of metabolic capabilities with potential biotechnological advantages. Microalgae are promising organisms for the sustainable production of metabolites of commercial interest, such as lipids, carbohydrates, pigments, and proteins. Several studies reveal that microalgae growth and cellular storage of these metabolites can be enhanced significantly by co-cultivation with growth-promoting bacteria. This review summarizes the state of the art of microalgae-bacteria consortia for the production of microalgal metabolites. We discuss the current knowledge on microalgae-bacteria mutualism and the mechanisms of bacteria to enhance microalgae metabolism. Furthermore, the potential routes for a microalgae-bacteria biorefinery are outlined in an attempt to overcome the economic failures and negative energy balances of the existing production processes.