How can synthetic biology reshape the supply chain of healthy raw materials for ergot sulfur, a "biological gold," with a production capacity ranging from 0 to 300 tons due to industrialization?

With technological iteration and cost reduction, ergotamine is transforming from a high-end raw material to a universal health ingredient, with enormous potential for future applications in the fields of medicine, food, and cosmetics.   

The following are the key technological paths from zero to industrial production:

Natural chassis optimization: Early research often used brewing yeast and Escherichia coli, but there were problems such as low yield and long fermentation cycle.

For example, Escherichia coli requires an external sulfur donor and carries a risk of endotoxins, while genetic modification of brewing yeast is complex. 

 

Lactic acid Kruve yeast: The Chinese team used GRAS certified lactic acid Kruve yeast as the chassis, and achieved a yield of 398.64 mg/L in a 5 L fermentation tank by heterologous expression of the Stereum hirsutum derived ergothionein synthase gene (ShEgt1 ShEgt2), combined with metabolic engineering optimization of precursor supply, which was 18 times higher than the initial strain, with a fermentation period of only 96 hours.

Its advantages lie in the absence of external sulfur donors, high genetic stability, and suitability for industrial promotion.   

By integrating multiple copies of ShEgt1-ShEgt2 into the genome of lactic acid yeast, the expression of synthetic enzymes is enhanced.   

Modify the metabolic pathways of histidine, cysteine, and methionine, such as overexpression of hisG, cysE, and metK genes, to improve precursor supply efficiency.   

Directly adding precursors (such as 20 g/L glucose+4 g/L histidine+10 g/L methionine) to the culture medium increased the shake flask yield to 188.17 mg/L.   

1. Culture medium and fermentation conditions pH stat control: In the fermentation of lactic acid yeast, automatic acid/alkali supplementation is used to maintain pH 7.0, avoiding acidic conditions that inhibit bacterial growth and enzyme activity.   

Carbon source gradient addition: Adopting batch sugar supplementation to avoid the inhibition of high concentration glucose on ergothionein synthesis and increase bacterial density.   

Mass transfer optimization: Adopting a high dissolved oxygen stirring strategy (30% -50% DO) to prevent sulfur oxidation and promote the transmembrane transport of precursor substances.  

 

Develop efficient air lift fermentation tanks to reduce damage to bacterial cells caused by shear forces, suitable for high-density cultivation.   

A certain research institute has achieved efficient production of ergothionein in a 3000 L fermentation tank, and the fermentation broth can be consumed directly without purification.

1. Intracellular product release and all aqueous phase extraction: High pressure homogenizer is used to crush the mycelium, combined with ceramic membrane filtration (50 nm) and ultrafiltration membrane (molecular weight cutoff of 300-1000 Da), to achieve efficient release and preliminary separation of ergothionein, avoiding the use of organic solvents.   

Desalination and decolorization: Electrodialysis desalinates to a conductivity of<100 μ S/cm, removing inorganic salt impurities. Macroporous resin (such as ADS-7) adsorbs pigments, making the filtrate almost colorless.   

Crystallization and drying: After concentrating to a concentration of 20% ergothionein, high-purity crystals (purity ≥ 99.97%) are obtained by natural cooling crystallization.   

Hyaluronic acid or trehalose is added as a protective agent during spray drying to reduce the damage of high temperature to ergot sulfur, and the yield is increased by more than 30%.