Increasing sugar production in saltwater to produce biofuel

In a recent paper by Shireesh Srivastava, Group Leader, System Biology for Biofuel, his team has successfully engineered a marine cyanobacterium to increase growth and glycogen (sugar) production in a simple medium.

Most biotechnological processes, including biofuel production, are dependent on low-cost and a sustainable supply of sugars and a nitrogen source. The sugars typically come from plants. Plants utilise a process called photosynthesis that uses light energy to convert CO2, a greenhouse gas, to biological components such as sugars, proteins and lipids. However, some bacteria, such as the cyanobacteria (also known as blue-green algae), can also perform photosynthesis and sugar production by fixing CO2. Cyanobacteria are found in both fresh and marine water. Marine cyanobacteria do not require freshwater, a resource that is becoming scarce, for their growth and sugar production. Moreover, the yield of sugars from cyanobacteria could potentially be much higher than that of land-based crops.

Unlike plant-based sugars, cyanobacterial biomass also provides a nitrogen source in the form of proteins. However, to improve the economic feasibility of marine cyanobacteria-based sugar production a significant improvement in the growth rates and sugar content is needed.                                      

Srivastava and team found that the engineered cells produced more than double the amount of glycogen compared to normal cells at all the concentrations of CO2 tested. Additionally, the engineered cells would not require bubbling of concentrated CO2. This is an important development in the utilisation of marine cyanobacteria for sugar production for biotechnological and biofuel applications. The work, sponsored by the Department of Biotechnology (DBT), was published in Open Source in the journal Biotechnology for Biofuels.

Additionally, the proteins that are present in the cyanobacterial biomass could also provide the nitrogen source for biotechnological applications.

Further reading:

Biotechnology for Biofuels
J.K. Gupta, P. Rai, K.K. Jain, S.Srivastava. 28 Jan 2020. Overexpression of Bicarbonate Transporters in the Marine Cyanobacterium Synechococcus Sp. PCC 7002 Increases Growth Rate and Glycogen Accumulation