Cyanobacteria have gained much attention as a rich source of bioactive compounds and have been considered as one of the most promising groups of organisms to produce them. One of the well-known and widely used representative, mostly in the food industry, is Arthrospira platensis (Spirulina platensis).
Growth of A. platensis requires a group of nutrients in the cultivation media, with the nitrate, phosphate, and carbon source being of the highest importance. Under systematic, continuous cultivation a build up of nutrients, organic matter and A. platensis metabolites is observed in the cultivation water, which acts as a growth inhibitor for A. platensis and is therefore an issue for the productivity in commercial plants. This fact shows the need to replace the media water when A. platensis production decreases, which leads to the production of large yearly amounts of Arthrospira purge water.
Therefore, an A. platensis production in tank based systems presents two key technological challenges:
- Reducing water usage in A. platensis production by increasing purge water recycling
- Repurposing the purge water after it is no longer able to be used for algae cultivation
The aim of the project is to use the metabolites from A. platensis purge water for the production of a complex nitrogen source. Extremophile yeasts do have the capability to convert the short chain sugars that are occurring in A. platensis purge water into valuable lipids and these do have the potential to serve as a valuable food product.
Therefore, the aim of the project is twofold: Firstly, the integration of a second biological process shall serve as a purge Arthrospira wastewater cleaning step. That is the cultivation of extremophile yeasts in the wastewater, that have the capability to convert the exopolysaccharides and media build up to valuable lipids, while the water is recycled and reused in A. platensis cultivation. Secondly, the produced biomass or parts thereof (yeast extract, lipids etc.) represent additional product streams with the potential to serve as a valuable food product of or a recycle stream for existing or as an organic alternative media for existing A. platensis production plants.
The implementation of a second biological step into algae cultivation systems, that makes use of the purge water, will be pursued. An extremophile yeast, Debaryomyces hansenii, a producer of valuable lipids, has been identified for this purpose. There is evidence that these two organisms could be cultivated on each other’s excreted metabolites and enable a combined production process. To enhance the profitably of the overall process valuable substances, a lipid fraction and a yeast extract from D. hansenii shall be identified, isolated and assessed in regards of their compliance to food and feed applications. The experiments in lab scale will be cultivations of A. platensis and D. hansenii on the respective purge water and an in depth analysis of all influencing effects. Furthermore, the isolation of lipids and yeast extract will be investigated. All experimental investigation will be analytically monitored, the developed new products will be characterized and data for validation will be gathered. The results of the experimental investigation will be technically assessed and contribute to the design of an integrated overall process for the valorization of side streams of the said process, by creating further products from and closing recycle loops for A. platensis production processes.
Purge to Value partners are:
Prof. Dr. Heike Frühwirth : Hochschule Biberach (HB), Germany
Dr. Baptiste Leroy : University of Mons (UM), Belgium
Dr. Thornthan Sawangwman : Ramkhamhaeng University (RU), Thailand
Muhamet Doertkardes : EnerGaia Co. Ltd. Thailand
Heike Frühwirth : firstname.lastname@example.org