Photoautotrophs-Bacteria Co-Cultures: Advances, Challenges and Applications

Abstract

Photosynthetic microorganisms are among the fundamental living organisms exploited for millennia in many industrial applications, including the food chain, thanks to their adaptable behavior and intrinsic proprieties. The great multipotency of these photoautotroph microorganisms has been described through their attitude to become biofarm for the production of value-added compounds to develop functional foods and personalized drugs. Furthermore, such biological systems demonstrated their potential for green energy production (e.g., biofuel and green nanomaterials). In particular, the exploitation of photoautotrophs represents a concrete biorefinery system toward sustainability, currently a highly sought-after concept at the industrial level and for the environmental protection. However, technical and economic issues have been highlighted in the literature, and in particular, challenges and limitations have been identified. In this context, a new perspective has been recently considered to offer solutions and advances for the biomanufacturing of photosynthetic materials: the co-culture of photoautotrophs and bacteria. The rational of this review is to describe the recently released information regarding this microbial consortium, analyzing the critical issues, the strengths and the next challenges to be faced for the intentions attainment.

Keywords: bacteria; bio-molecules; biomass; co-culture; microalgae; omics; sustainability.

Figure 1

A schematic timeline representing the main milestones results related to the microbial consortia statement. Reprinted with permission from Qian et al. (2020). Biotechnological potential and applications of microbial consortia. Biotechnology Advances [32]. Copyright (2020) Elsevier.

Figure 2

Microalgal–bacterial consortium and its biotechnological applications. Reprinted with permission from Zhang et al. (2020). Microalgal–bacterial consortia: From interspecies interactions to biotechnological applications. Renewable and Sustainable Energy Reviews [18]. Copyright (2020) Elsevier.

Figure 3

Schematic representation of the possible routes intended for microalgae–bacteria co-cultures in the biorefinery scenario. With the scale-up cultivation of these algae/bacteria consortia, there are many possible applications, e.g., the production of high-value-added compounds, reduction of CO₂ emissions, and by the reuse of biomass the production of bio-fertilizers, water bio-sanitation, production of alternative and sustainable energies. Reprinted with permission from González-González et al. (2021). Toward the Enhancement of Microalgal Metabolite Production through Microalgae–Bacteria Consortia. Biology [93]. Copyright (2021) MDPI.

Figure 4

The synergistic interaction of microalgae and other microbes (such as bacteria) for wastewaters treatments. The consortium cells by metabolite exchange (organic compounds, O₂, CO₂ and growth-promoting factors) play important role in the secondary and tertiary treatment of these waters; moreover, the harvested biomass can further be used as feedstock for biofuel or biochemical production. Reprinted with permission from Qian et al. (2020). Biotechnological potential and applications of microbial consortia. Biotechnology advances [32]. Copyright (2020) Elsevier.

Figure 5

Consortia microalgae based can stimulate the plant growth-promoting bacteria (PGPB) allowing a sustainable agriculture. In detail, the microalgae cells and PGPB establish a beneficial exchange of nutrient molecules, and together enhance plant growth by producing phytohormones and other growth stimulants. Furthermore, this consortium can prevent the occurrence of certain plant diseases with particular suppressive mechanisms. Reprinted with permission from Kang et al. (2021). Potential of Algae–Bacteria Synergistic Effects on Vegetable Production. Frontiers in Plant Science [102]. Copyright (2021) Frontiers.

Figure 6

Omics techniques for the construction of an efficient consortium. Different experimental and computational methods can be applied on co-cultured cells to reach a deep knowledge and characterization of the microbial communities. Reprinted with permission from Zuñiga et al. (2017). Elucidation of complexity and prediction of interactions in microbial communities. Microbial biotechnology [119]. Copyright (2017), Wiley.