Light Happy Yeast May Change Our Approach to Biofuels

Light Is Life

Almost all energy in human civilization is ultimately derived from the sun. Food, biomass, and wood grow thanks to sunlight. And coal, gas, and oil are made of dead plants millions of years ago. Even winds are the result of the sun warming the atmosphere. And, of course, today, we have solar panels.  Considering how much of our energy needs are covered by living organisms harnessing the sun's power, the concept of biofuels makes sense.

The problem is that first and second-generation biofuels, using crops like maize and sugarcane or farming residues, tend to have a rather poor energy yield due to how much fossil fuels and fertilizers are used to grow these crops.

Source: Unsplash

Third-generation biofuels are looking to use algae instead, something we discussed in further detail in our article “Algal Biofuel: The Next Energy Revolution?”.

But what if we could make any organisms able to perform photosynthesis? What has so far been a pipe dream has been partially achieved by researchers at Georgia Tech.

Light-Powered Yeast

Yeast is maybe the best-understood microorganism in the world. Humans have leveraged yeasts' biochemical abilities to produce bread, alcohol, and fermented milk products since the dawn of civilization.

Yeasts are also one of the most common organism “models” in biology laboratories. And important bio-factories for plenty of medicines and useful biomolecules.

Still, yeasts need to be fed with sugar or other compounds to stay alive. At least, that was true until Anthony Burnetti, a research scientist working in Associate Professor William Ratcliff’s laboratory, managed to make yeast able to harvest the energy of light.

“All we needed to do was move a single gene, and they grew 2% faster in the light than in the dark. Without any fine-tuning or careful coaxing, it just worked.”

Completely New Type Of Yeasts

The team is experienced in changing yeast, a common and ubiquitous organism with new and unexpected potential. Most notably, they previously managed to transform the unicellular yeast into a complex multicellular organism in the “Multicellularity Long-Term Evolution Experiment”.

Source: Georgia Tech

A limit to the growth of these multicellular yeast organisms was accessing oxygen in the inner “tissues”. This is why they went on to make yeast a photosynthetic organism.

To do so, they added a protein, the rhodopsin, to the yeasts. This protein is known to do some photosynthesis without superior plants' complex proteins and biomolecules (like chlorophyll).

Just by adding one gene coding for a rhodopsin protein, the yeast could catch light and grow quicker. The increase was modest, just a +2% growth rate, but significant because of the simple change. And this increased growth has not been optimized yet.

Biofuel With Synthetic Biology

So far, biofuel research has been trying to modify already photosynthetic plants (maize, sugarcane, or algae) and make the process efficient enough to make economic sense.

But this hit several hurdles, as the biomaterials in superior plants and crops like maize are not readily available, and transforming them into ethanol means a lot of energy losses.  Meanwhile, Algae are more promising, but cultivating them without contamination is far from a simple task.

On the contrary, growing yeast is a well-understood process routinely performed in massive industrial processes. Turning yeast into a replacement for algae could open the way to new methods for synthesizing biofuels. Instead of relying on complex processes to grow algae, we could engineer yeast or bacteria so they can grow from just sunlight and benefit from the fact that these organisms are much easier to grow in industrial amounts.

Bioengineered Fuel Stocks

Overall, this is still a very young and prospective segment of biofuel research and bioengineering. So, the companies most likely to try to make it a reality will need high levels of expertise in synthetic biology and/or biofuel production.

The list below is just a suggestion of which companies might see potential in Georgia Tech's researchers' discovery.

1.  Reliance Industry

Reliance Industry is a massive Indian conglomerate, the largest private company in the country, active in telecom, textiles, and energy. In 2022, it was the first Indian company ever to reach $100B in revenues.

Reliance has announced in 2022 its entry into the algal biofuel market, boasting “one of the largest algae cultivation systems in the world”. Until now, its energy portfolio was mostly refinery and petrochemical plants. With this algal project, it would be able to start production and use the abundant sun in India (as well as uncultivated deserts) to reduce the country's extreme reliance on foreign fossil fuel imports.

The company is also active in the production of biogas from agricultural wastes, making it India’s largest bioenergy producer.

2. Ginkgo Bioworks

The company is producing on-demand organisms for specific applications. This includes biomedical applications, but also plenty of industrial and material sciences programs as well.

Gingko is exactly the type of company that large industrial conglomerates like Reliance could turn to for engineering a custom yeast dedicated to biofuel production.

Gingko Bioworks has diversified its applications widely with many research programs and partnerships:

• Cannabinoids
• mRNA vaccine production and nucleic acid medicine
• Food proteins
• Biological fertilizer production in partnership with Bayer
• Programmable microbes for gut diseases
• Microplastics bioremediation
• Biosecurity and pathogens detection
• Recycling waste and contaminants

It makes money by being first paid upfront for the development process and then through royalties on the finished product.

2023 was a bountiful year for Gingko, with tens of partnerships, including:

• $331Mdeals with Pfizer.
• $490Mdeal with Merck to optimize biologics manufacturing.
• $406M deal with Boehringer Ingelheimfor undruggable targets.
• Collaboration with Biogen and Novo Nordisk for undisclosed amounts.

Source: Gingko Bioworks

Ginkgo Bioworks also partners with all the major agricultural corporations, most of which have some interests in biofuel production and microbiology.  A few of these include Bayer, Cargill, Syngenta, Corteva, ADM, Exacta, and more.