Accustomed to using systems like Escherichia coli, Saccharomyces cerevisiae, and CHO cells, many biotech professionals–even seasoned experts–lack a working familiarity with microalgae biotechnology and the benefits of microalgae in biomanufacturing. So, it’s common for our team to hear the question, “why microalgae?”
When most people in biotech think about cellular biomanufacturing systems, they think of the traditional workhorse classes: bacterial (e.g. E. coli), yeast (S. cerevisiae), insect (e.g. Sf9) and mammalian (e.g. CHO and HEK293) cells.
With significant research investment into these cell systems over the preceding half-century, the biotech industry has long capitalized on its ability to express target bioproducts in these cells. Yet, not every bioproduct can be most effectively made in these well-characterized cell chassis. Bioprocesses are far from being one-size-fits-all, especially when dealing with novel target products. Each cell chassis offers specific advantages and disadvantages that drive their applications. Thus, it stands to reason that less understood and less characterized cell systems may provide unique characteristics and benefits as biomanufacturing chassis. Yet, the biotech industry has had to rely on the available cellular tools, with little time to develop complete biomanufacturing solutions for new systems–however valuable their long-term potential may be.
To accommodate this industry need, Provectus Algae has developed an end-to-end biomanufacturing platform that can produce high-value chemicals, speciality ingredients, and biologics using any microalgae species. In doing so, we have opened the door to a whole new cell system class, expanding the slate of potential biomanufacturing chassis and complementing existing ones.
Importantly, we elected to work with these microbes in large part because of specific microalgae characteristics and the advantages they offer in biomanufacturing. We choose these fantastic microbes because of their:
By combining our technologies with the natural benefits of microalgae, biomanufacturers can unlock new commercial bioprocesses and make a wide range of high-value products from microalgae. So, let’s jump into more detail about the commercial benefits of microalgae biomanufacturing, starting with an introduction to microalgae’s transformative role on planet Earth.
Microalgae have enjoyed a long and successful history on our planet. Though it’s difficult to pinpoint the exact timeline, evidence suggests that cyanobacteria (also known as blue-green algae) originated as early as 3.4 billion years ago. The evolution of oxidative photosynthesis in the following half-billion years led to the Great Oxidation Event, where atmospheric oxygen levels rose significantly, massively altering the course of life on Earth.
Photosynthetic eukaryotic microalgae first cropped up between 1 and 2 billion years ago. Researchers think that the origin of eukaryotic microalgae stimulated another increase in atmospheric oxygen levels, with concentrations rising from 1-5% to 20%. This further increase in oxygen levels opened the door to an explosion of diverse, complex life on Earth. Today, microalgae produce approximately half of the world’s oxygen.
Since then, microalgae evolved to inhabit nearly every ecosystem on the planet, including marine, freshwater, and terrestrial habitats. Specific microalgae species have even prospered in some of the world’s most challenging environments. For example, the green algae, Dunaliella parva, acts as the sole primary producer found in extremely saline waters of the Red Sea. As another example, there are communities of “snow” microalgae adapted to Antarctica and its cold temperatures, high UV, and unusual day-night cycles, including Chloromonas species.
Within these many unique ecosystems, photosynthetic microalgae play a crucial role as the primary source of chemical energy for many food chains. In short, they have cemented themselves as integral species within the ecosystems they have each come to inhabit.
Cellular systems need rapid growth rates and effective gene editing workflows to be viable for biomanufacturing. Though not all microalgae behave identically, microalgae growth rates are generally quite high. In addition, researchers have successfully applied genetic engineering approaches to manipulate several microalgae genomes. While significant work needs to be done to develop methods applicable to a broader range of species, recent advances in microalgae biotechnology and synthetic biology, including efforts at Provectus Algae, have made genetic engineering increasingly efficient and practical, especially in Chlamydomonas reinhardtii.
Over time, an impressive number of different microalgae species evolved. A conservative estimate places the total diversity at around 70,000 microalgae species, with other estimates reaching 200,000 to several million. Natural selection pushed individual species to evolve specific biochemical abilities and metabolic characteristics to thrive in their specific ecosystem and its unique demands. For example, coastal microalgae adapted to deal with turbulence and capitalize on nutrient-rich environments and low-light conditions. As another, ocean microalgae evolved to survive the open ocean’s high irradiance and minimal nutrient composition. Altogether, each species ended up with unique metabolisms and natural product profiles to create the exact organic materials needed in their specific niche.
With their natural affinity for making novel functional bioproducts, microalgae hold significant commercial potential across many industries. We now know that microalgae can produce various high-value chemicals, specialty ingredients, and biologics like pigments, flavors, fragrances, growth factors, fatty acids, antioxidants, oligosaccharides, proteins, terpenes, amino acids, peptides, and beyond.
However, microalgae researchers have only explored a small selection of microalgae species (~15) for commercial potential and at-large scale cultivation. Thus, there remains significant untapped potential for exploring the many less uncharted microalgae species for the biodiscovery of functional algae bioproducts and precursors. Using synthetic biology approaches, users can further enhance the expression of natural microalgae products, control metabolic flux, engineer new biochemistries, or express recombinant gene products. Over time, microalgae research may find that certain underutilized species make for superior biomanufacturing chassis for specific recombinant biologics.
Furthermore, the diverse metabolic characteristics of microalgae species also offer sustainability benefits. By more completely exploring the metabolites found in microalgae species, researchers can identify opportunities to replace molecules made synthetically with bio-based ones. Given that many common solvents and chemical ingredients are still petroleum-derived and environmentally hazardous, the reduction of synthetic chemical manufacturing through biodiscovery is yet another potential benefit of microalgae.
To bring more microalgae species online for bioproduction, Provectus Algae is building a microalgae library and amassing a multi-omics database to decipher specific microalgae characteristics and discover novel algae bioproducts. Using automation, machine learning, bespoke biomanufacturing tools, and our Precision Photosynthesis™ technology, we can also quickly identify the ideal conditions to grow microalgae species.
Though commercial bioprocesses have historically used various cell types, these cells have overwhelmingly been heterotrophic, meaning they consume organic matter for energy, nutrition, and growth. The development of autotrophic (or photosynthetic) bioproduction systems can significantly expand the biomanufacturers’ toolkit. Instead of generating CO2 and consuming expensive resource-limited inputs, photosynthetic biomanufacturing can reduce carbon emissions and increase bioprocess sustainability.
As some of the world’s most productive photosynthetic organisms, microalgae are particularly well suited to drive the mass adoption of photosynthetic biomanufacturing. In effect, microalgae bioprocesses use light and CO2 to make valuable biochemicals, with microalgae carbon sequestration occurring as a bioprocess by-product. Photosynthetic microalgae provide biomanufacturers with a tangible mechanism to lower their carbon footprint and reach carbon neutrality goals.
Though terrestrial plants have been explored for biomanufacturing and extracting natural products, they present significant limitations compared to microalgae. Chiefly, microalgae grow more rapidly and fix carbon as much as 10–50 times faster than terrestrial plants. Importantly, large-scale microalgae cultivation does not require arable land and needs a much smaller commercial footprint, especially for photobioreactor-based bioprocesses. Thus, plant biomanufacturing efforts must occur in specific geographic locations while competing with agriculture needed to feed the planet. Overall, microalgae offer a much more universal approach to photosynthetic biomanufacturing.
Using photosynthesis, microalgae bioprocesses lower the need for cell culture media ingredients and nutrients, including essential building blocks (like, amino acids and nucleotides) and energy-rich molecules (like, glucose). In addition to consuming CO2, microalgae bioprocesses also reduce the need to produce, store, and distribute raw materials needed by heterotrophic cells. This can further reduce the total carbon footprint of biomanufacturing sites and the ecosystem that supports them.
Biomanufacturers must also consider the cost of a cellular system to ensure healthy margins and viable economics for their products.
In particular, media inputs can be a major expense for heterotrophic bioprocesses. Instead, biomanufacturers can capitalize on microalgae’s ability to generate chemical energy from light to turn CO2 into valuable microalgae-based products. Due to their photosynthetic nature, microalgae generally need less nutrient-rich media, which in turn reduces cultivation costs. Instead of acquiring an array of cell culture ingredients and using expensive high-nutrient media, biomanufacturers can get microalgae species to make their own raw materials.
Using light and CO2 as primary inputs can also help biomanufacturers trim and de-risk their supply chain. Microalgae users can save on shipping expenses and reduce opportunity costs associated with downtime due to raw material delays and shortages
Another advantageous microalgae characteristic is their capacity to mitigate bioprocess risks and increase consumer safety. For one, microalgae are not known to harbour human pathogens. Since microalgae use minimal nutrient media conditions and are so distinct from human cells, dangerous pathogens often struggle to gain footholds in microalgae culture. In effect, this drastically lowers the likelihood of contamination events from disease-causing entities, like viruses and prions.
Along the same lines, biomanufacturers can also tap microalgae to generate critical animal origin free (AOF) specialty ingredients and biochemicals. Increasingly, both regulators and manufacturers see the risk-reducing advantages of AOF materials, particularly for biopharmaceuticals. Additionally, AOF ingredients offer significant upside to vegan food and beverage companies as well as cosmetic companies looking for animal-free ingredients for safety, consumer demand, and environmental reasons.
Furthermore, many microalgae species are inherently safe for human use. This is highlighted by the fact that humans have been eating microalgae for health and nutrition for thousands of years. In fact, the US FDA considers a number of microalgae species as “generally regarded as safe” (GRAS) for consumption. In addition to lowering product risks, biomanufacturers can even use microalgae cells to package, protect, and deliver molecular products. Microalgae cells can serve as delivery vehicles for pharmaceuticals, nutraceuticals, cosmeceuticals, and nutritionally enhanced feedstock. By keeping molecular products inside microalgae cells, biomanufacturers can also enjoy greater product stability and the reduction of costly downstream purification processes.
Post-translational modifications (PTMs), like glycosylation, can tremendously impact a molecule’s bioactivity. To maximize bioactivity and product quality control, biomanufacturers must often ensure consistent PTM. Unfortunately, bacteria often lack PTM capabilities equivalent to eukaryotes. Though yeast can perform most PTMs, they struggle to replicate specific glycosylation patterns, often resulting in hyper-glycosylated biomolecules.
On the other hand, microalgae can perform all critical modification types, even displaying glycosylation patterns more similar to humans than E. coli or yeast. In addition, like mammalian cells, eukaryotic microalgae express chaperones and complex protein-folding machinery. Thus, biomanufacturers can use microalgae to express and correctly fold complex proteins that bacteria or yeast cells cannot make.
In some cases, PTMs like glycosylation events can have a deleterious effect on recombinant bioproducts. For example, specific glycosylation patterns can lead to adverse immune responses and decrease performance consistency. In those cases, biomanufacturers often need to remove glycans enzymatically or by knocking out genes. Both processes can be time-consuming and costly.
Microalgae offer users another mechanism. Instead of transforming the nuclear genome to express microalgae products, biomanufacturers can incorporate recombinant genes into the chloroplast genome. Since chloroplast genomes lack glycosylation machinery, biomolecules expressed there will lack glycans.
Importantly, expressing target microalgae products in chloroplasts does not drastically reduce cellular productivity. Recombinant proteins made in C. reinhardtii chloroplasts can represent up to 20% of the total soluble protein from microalgae cells.
Additionally, microalgae chloroplasts do not have a secretion pathway like the endoplasmic reticulum and Golgi apparatus do. Thus, biomolecules produced in microalgae chloroplasts are sequestered there, which is especially advantageous for cytotoxic or unstable bioproducts. In addition, this can simplify downstream purification since biomanufacturers can easily separate chloroplasts from the rest of the cell and it contents.