There’s an exciting reason to celebrate Fungus Day this year as the world is looking for sustainable and nutritious food alternatives. The filamentous fungus, Aspergillus oryzae, traditionally used in food fermentation, has been genetically engineered to create a nutritious and flavourful food source. The study “Edible mycelium bioengineered for enhanced nutritional value and sensory appeal using a modular synthetic biology toolkit” in Nature Communications used synthetic biology to enhance the mycelium of Aspergillus oryzae to produce higher levels of two critical nutrients: ergothioneine and heme, as summarised by Ankita Chattopadhyay in this #FEMSmicroBlog. #MicrobiologyEvents
About the food producer Aspergillus oryzae
Aspergillus oryzae, also known as koji mould, is best known for producing soy sauce, miso, and sake. It’s been a staple in East Asian cuisine for centuries, thanks to its ability to break down complex proteins and starches.
While Aspergillus oryzae is non-toxic, its mycelium is rich in nutrients like proteins, essential amino acids, heme, and ergothioneine. Heme is crucial for oxygen transport in the blood and a critical source of iron. Similarly, ergothioneine is a powerful antioxidant that protects our cells from oxidative stress.
This makes Aspergillus oryzae a potential food source and a nutritional and sustainable alternative to meat and burgers. That’s why the study “Edible mycelium bioengineered for enhanced nutritional value and sensory appeal using a modular synthetic biology toolkit” aimed to engineer Aspergillus oryzae to increase its ergothioneine and heme levels.
The power of synthetic biology
The study used the CRISPR-Cas9 toolkit to edit the genome of Aspergillus oryzae in regions that do not affect essential functions. This allowed them to genetically engineer a strain whose edible biomass contains increased intracellular levels of ergothioneine and heme.
For ergothioneine production, the researchers introduced egt-1 and egt-2 from the common bread mould Neurospora crassa into Aspergillus oryzae. Their gene products convert cysteine, histidine, and S-adenosylmethionine into ergothioneine.
Overexpressing these genes led to ergothioneine levels that were even higher than expected. These levels were similar to those in oyster mushrooms, the dietary mushroom known for having the highest ergothioneine content.
To improve heme production, they modified the expression levels of the key heme biosynthetic enzymes in Aspergillus oryzae. They either edited the upstream promoters or mutated key residues in motifs that are involved in feedback inhibition. Expressing two copies of soy leghemoglobin further acts as heme sinks to minimize cytotoxicity from elevated levels of free heme.
Overall, intracellular heme levels in the biomass of the engineered strain were four times higher than in the wild-type strain. These levels are fairly close to those in leading plant-based meat alternatives.
After harvesting, the biomass of the engineered strain was red, with the colour retaining after being cooked, enhancing its meat-like appearance. Moreover, this modified strain contains all essential amino acids with no change in its growth yield and protein compared to the wild-type strain.
Fungi as the potential superfood of the future
The implications of this study are extensive. As the global population grows, so does the demand for sustainable and nutritious food sources. Traditional agriculture, especially livestock farming, has a huge environmental footprint. Hence, fungus-based mycelium is a great alternative as it can be produced with far fewer resources and a lower environmental impact. At the same time, tailoring the nutritional content of food helps address specific dietary needs.
The resulting engineered Aspergillus oryzae is safe to consume, while its high protein content and elevated heme and ergothioneine levels make it a promising alternative for the future of food.
As such, this study exemplifies how synthetic biology can create food that is sustainable and packed with necessary nutrients. The future of food might just be fungal—and that’s something to celebrate.
If you are interested in sharing similar research at the FEMS MICRO Milan 2025: Congress & Exhibition, 14-17 July, make sure to submit your abstract to the Biotechnology topic track. We hope you can join us in magnifying microbial impact. Submissions are now open!
Ankita Chattopadhyay is a microbiology researcher passionate about anti-fungal drug resistance and pathogen evasion strategies. With research training in fungal cell biology and adaptation mechanisms at the University of Edinburgh, UK and a foundational background in applied microbiology from VIT University, India, she aims to develop strategies to improve existing treatments and discover new drug targets for tackling fungal infections. Outside of the lab, she enjoys hiking, travelling, writing, and occasionally playing badminton.
About this blog section
The section #MicrobiologyEvents for the #FEMSmicroBlog reports about events and meetings relevant to our network. These include world awareness days, FEMS-sponsored meetings or meetings of Member Societies and many more.
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