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

Abstract

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.

Keywords: biorefinery; growth-promoting bacteria; metabolites; microalgae; mutualism.

Figure 1

Synthetic mutualism between Chlorella spp. and the microalga growth promoting bacteria (MGPB) Azospirillum brasilense. (a) Scanning electron microscopy. (b) Epifluorescence microscopy. Auto-fluorescence of microalgae appears in orange while bacteria appear in green as result of fluorescent in situ hybridization (FISH) using three specific probes targeting Eubacteria (FAM dye) and one specific probe for A. brasilense (CY3 dye). Arrows show cells of A. brasilense attached to the microalga. (c) Model of the synthetic interaction. Az, Azospirillum brasilense; Cs, Chlorella sorokiniana.

Figure 2

Schematic model of a microalgae–bacteria sustainable and cost-efficient system for the production of several metabolites within a biorefinery using different biological routes.