Marine microalgae enriched in carbohydrates for concomitant nutrient recycling and green chemicals production
Microalgae offer a large potential to be a sustainable and renewable feedstock for a bio-based production. Our aim for this project is to investigate processes for optimal and sustainable production of carbohydrates from marine microalgal biomass. This will be done by identifying potential high-carbohydrate containing strains, identifying optimal cultivation conditions, using CO2 from flue gas streams for cultivation, and evaluating potential applications based on sugar composition. The development of CO2-neutral fuels and chemicals is one of the most urgent challenges facing our society, i.e. to reduce gaseous emissions and their consequential climatic changes, greenhouse and global warming effects. Microalgae is expected to offer new opportunities for the production of bio-based commodities, potentially developing new technologies for the long-term replacement of fossil resources.
In this work, marine microalgal strains with high growth rates and a capacity to accumulate high concentrations of carbohydrates will be identified. The use of marine strains largely decreases the need for freshwater, reducing competition for an already under-pressure resource. Cultivation conditions that improve the productivity or content of carbohydrates in these strains will be identified and optimized through physiological and metabolic characterization. These carbohydrates (and amino acids) could potentially have use as feedstocks for the production of other cell factory systems (yeast, bacteria), reducing reliance on costly agricultural carbon sources. As such an assessment of the fermentability of sugars derived from hydrolysed algal biomass will be performed and the feasibility of such an approach evaluated.
In addition, this project will investigate the use of flue-gases as sustainable carbon sources (CO2) to support microalgal growth. The supply of high concentrations of CO2 is critical in achieving high growth rates, and identifying cheap and sustainable sources will be critical for large-scale microalgal cultivation, where the requirement of CO2 could be in the order of tonnes per hectare per year. The use of flue gases does come with some problems, particularly sulphurous and nitrous dioxides that could potentially be present at levels inhibitory to algal growth. Identifying both strains that can cope with these compounds and strategies to alleviate their effects will be critical to the use of flue gases.
Microalgae also have large requirements for nitrogen and phosphorus nutrients; these may typically be supplied as commonly used agricultural fertilizer. This may pose future problems as these resources become more in demand, but can also add significantly to the cost of production. Extracting nutrients from more sustainable sources such as waste or process water from industry or municipal infrastructure may reduce reliance on costly fertilizers, while offering the additional benefit of mitigating energy intensive water cleaning processes. The effect of some promising nutrient sources on growth and physiology will also be evaluated in this project.
In this project, we work closely with SP Swedish Technical Research Institute and Gothenburg University.
This project is funded by Formas.