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Last updateThu, 29 Dec 2022 2pm

Back You are here: Inicio Environment Technological offers Achieving a null CO2 footprint by cyanobacteria

Achieving a null CO2 footprint by cyanobacteria

Scientists at the National Biotechnology Centre are researching to develop industrial processes with a zero CO2 footprint based on recombinant strains of cyanobacteria. They have obtained a cyanobacteria strain that produces sucrose efficiently from CO2, and does not need osmotic stress neither high salinity environments, making it easier to cultivate. Scientists are now working to transfer the method to industry.

Cyanobacteria in  a pool. Picture: Christian Fischer/Wikimedia

Among the many options being considered to reduce atmospheric CO2 emissions, one of the most sustainable is the use of microorganisms that capture environmental CO2 and transform it into some kind of molecule of interest. This strategy would not only reduce dependence on fossil fuels as a source to obtain these molecules, but would also generate new bioprocesses with a zero-carbon footprint.

Cyanobacteria are among the organisms with the highest photosynthetic yield, which makes them excellent candidates for these biotechnological processes.

The downside of these photosynthetic bacteria is, however, that they have a limited capacity to synthesise molecules of interest. An alternative is to design cyanobacteria capable of producing intermediate molecules from CO2 efficiently. Afterwards, the intermediate molecules can be used as a starting point for the production of molecules of interest by a second bacterium with a high biosynthetic capacity.

Searching for more efficient bacteria

A team at the CSIC's National Biotechnology Centre (CNB, which stands for Centro Nacional de Biotecnología) has developed a procedure based on a recombinant strain of the cyanobacterium Synechococcus elongatus, which absorbs CO2 and transforms it very efficiently into sucrose, a molecule that can be easily used by other organisms for the synthesis of any metabolite of interest.

The recombinant cyanobacterium Synechococcus elongatus obtained at the CNB has been designed following computational methods and has multiple advantages over similar existing bacteria

In this way, the sucrose produced can then be used to feed other biotechnological processes based on microbial systems, such as the production of bioplastics and natural products such as flavonoids.

The recombinant cyanobacterium Synechococcus elongatus obtained at the CNB has been designed following computational methods and has multiple advantages over similar existing bacteria. One advantage is that the cyanobacterium has a growth-coupled sucrose production and does not require a high salt concentration and osmotic stress environment. Salt independence allows maintaining a constant sucrose production without the need to implement costly two-step bioprocesses, growth and production.

A picture of what it might look like a biofactory for growing cyanobacteria in tube channels and produce PHA or other sucrose-fed bioproducts from other bacteria in traditional industrial fermenters.

In addition, the continuous production of sucrose allows the carbon source to be on-site, saving production and transport costs. In other words, such a biofactory could be coupled with another industrial process that generates CO2, which, instead of being emitted into the atmosphere, would be channelled to feed the biofactory.

Juan Nogales Enrique, principal investigator of the project at the CNB, explains that "the patent covers the sucrose production phase by the cyanobacteria. We are already trying to validate a bioprocess that also includes the production of polyhydroxyalkanoates (PHA), microbial polymers with plastic-like properties and therefore also known as bioplastics, as metabolites of interest. The strain can already be transferred."

The goal, Nogales explains, would be to scale up the sucrose production process in industrial bioreactors and use the high-sucrose supernatant (5-10 g/L) to feed sugar-based industrial processes.

Such a biofactory could consist, he adds, 'of circular bioreactors which could be filtered to obtain sucrose. The cyanobacterial biomass could be used for the extraction of pigments or other traditional products of interest that are already being extracted from these cyanobacteria'. Moreover, the bioreactors could be placed "in the same biofactory where the final molecule of interest is produced, which would save transport and other costs," he concludes.

 

Contact:

Centro Nacional de Biotecnología (CNB)
Deputy Vice-Presidency
for Knowledge Transfer-CSIC
Tel.: +34 915854306
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