From the ocean to sustainable biorefinery: the dormant potential of seaweed

The historical dependence on oil and other fossil fuels has led to significant environmental challenges, which are exacerbated by the rapid growth of the global population. Additionally, biotechnology processes that require cultivating microorganisms depend on the utilization of sugars and other compounds as raw materials that could instead be used to feed humans and animals. This fact generates resources competition. In order to alleviate this situation, it is imperative to achieve new, innovative, and greener bioprocesses from different raw materials. Macroalgae, also known as seaweed, offers a promising solution raw material for many reasons: since cultivation of seaweeds does not require of arable land and no freshwater, there is no competition with terrestrial crops; in addition, seaweeds grow relatively fast accumulating vast amounts of interesting sugars that can be used in environmentally friendly bioprocesses; finally, Norway is one of the major seaweed reservoirs in the world. Unfortunately, seaweed related sugars are atypical, and common microorganisms used in industry lack the ability to use them. Hence, our project aims to investigate and exploit the natural mechanisms of the native microbiota that grows on the surface of seaweed to break down and use these sugars. The knowledge and tools generated will be implemented in industrially relevant microorganisms, also called cell-factories, via genetic modifications to enable the utilization of sugars from seaweed by these microorganisms. On top of that, these cell-factories have been previously engineered to produce relevant molecules such as amino acids, hence production of these relevant molecules will be also proven from seaweed sugars. Finally, the newly generated seaweed-based cell-factories will be tested at different working volumes in bioprocesses with real seaweed and as proof-of-concept of a sustainable biotechnological approach that has the potential to impulse the circular bioeconomy.

Historical reliance on oil and other fossil fuels is dragging serious environmental problems, worsened by increased population growth. Therefore, there is a need for efficient new conversion technologies. Seaweed is a promising feedstock for microbial bioprocesses due to its high growth rates, great biomass production yields, abundance of fermentable carbohydrates, lack of arable land needed and no freshwater requirement for cultivation. However, at present, the fermentative use of seaweed is quite underexplored. Challenges revolve around the recalcitrance of seaweed polysaccharides and the crude mixture of seaweed sugars, which differ substantially from terrestrial crops. The WeedNERY project aims to develop the knowledge and technology to enable access to brown and red seaweed carbohydrates for microbial processes. Bioprospecting through metagenomic and bioinformatic studies is suited to gain access to seaweed degradation enzymes by studying the enzyme space of seaweed degrading microbiota. The identified enzymes could be used to engineer microbes for proper utilization of macroalgae as promising biomass for low-carbon bioeconomy. Uncovering the mechanisms of gene regulation under specific conditions is of fundamental importance in biotechnology, yet genetic alterations due to the presence of non-native substrates have rarely been studied and applied. Here, we will apply a novel approach based on the deactivated CRISPR technologies to transcriptomic-driven optimal seaweed-based biofactories. In addition, engineering feedstock access will be coupled to production of selected compounds to strengthen the biorefinery concept and the circular economy. We have chosen as target compounds the essential amino acid L-lysine, the compatible solute ectoine, and the precursor of immunosuppressant and antitumor bioactives L-pipecolic acid, all derived from a common biosynthesis pathway. To go beyond proof-of-concept, seaweed-based bioprocesses in bioreactors will be shown here.