Revolutionizing animal feed: China produces protein from coal-derived methanol

As global demand for animal feed reaches unprecedented heights, Chinese researchers have developed an innovative method to produce protein using methanol derived from coal, which is cost-effective and highly efficient. 

This innovation comes at a crucial time as the global animal feed market, estimated at $570.72 billion in 2022, is projected to grow at a compound annual growth rate (CAGR) of 4.6 percent from 2023 to 2030.

It's the first time protein production from coal has become economically viable. 

With a soaring global population leading to increased food demand, there has been an increase in demand for use of protein for animal feed. China, in particular, is having to navigate a severe shortage of protein resources.

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Despite being a leader in pig and aquaculture production, China heavily relies on imported soybeans for animal feed, importing approximately 100 million tons annually.

Hence the urgency to develop quick, efficient methods of producing high-quality proteins, and biotechnology synthesis seems to offer a positive solution.

One of the simplest ways is to convert food and agricultural by-products - such as corn steep liquor, distillers grains and straw - into higher-value protein products through microbial transformation. 

However, their inconsistent supply and quality add to the challenges of making industrial production.

Industrial fermentation

Another method is industrial fermentation, which requires using chemicals that produce energy. Methanol is one such chemical which can be cheaply derived from coal.

At the Tianjin Institute of Industrial Biotechnology, at the Chinese Academy of Sciences (CAS), scientists led by Wu Xin have been researching and developing this approach

"Coal, with a global reserve of about 1.07 trillion tons, can be converted into methanol through coal gasification," Wu wrote in a paper published in the journal China Science Bulletin. "Methanol mixes well with water, offering high efficiency in fermentation processes compared to gaseous substrates and eliminating the need for specialized fermentation equipment."

The team has developed a protein production technology that is cheaper than traditional protein biosynthesis.

Methanol is used to grow the yeast strain Pichia pastoris (P. pastoris) used in this method. However, due to methanol's toxic nature and intricate pathways, approximately 20 percent of it is lost during the process and turned into carbon dioxide and water instead. This reduces the overall efficiency and cost-effectiveness of the protein production process.

"Research on synthesizing cellular protein from methanol began in the 1980s, focusing mainly on strain selection and production process optimization," Wu said. "Yet, due to high costs, methanol-synthesized protein products could not compete with soy protein and have not been produced on a large scale."

Identifying efficient strains

The team collected more than 20,000 yeast samples from vineyards, forests and marshlands across China, and identified strains that can efficiently use various sugars and alcohols as carbon sources.

By knocking out specific genes in a wild-type Pichia pastoris strain, they engineered a yeast with significantly improved methanol tolerance and metabolic efficiency. This engineering dramatically boosted the targeted conversion of methanol to protein.

Through the targeted disruption of specific genes in a conventional Pichia pastoris strain, the researchers engineered a yeast variant with markedly enhanced methanol tolerance and metabolic efficiency. This genetic modification substantially boosted the targeted conversion of methanol to protein.

The high conversion rate makes this protein production method very economical.

Significantly higher protein content

"It doesn't require arable land, is unaffected by seasons and climate, and is a thousand times more efficient than traditional agricultural practices," Wu said. "Moreover, the protein content in the microorganisms ranges from 40 to 85 per cent, significantly higher than in natural plants."

These organisms also contain a complete amino acid profile, vitamins, inorganic salts, fats and carbohydrates, enabling them to partially replace fishmeal, soybeans, meat and skimmed milk powder in various applications.

The research team has already initiated industrial-scale demonstrations, producing thousands of tons of this protein in a plant. 

Microbial proteins are exceptional protein sources because, unlike soy protein, they are nutritionally rich and lack allergens but there is currently a limited availability of microbial protein products in the market. The U.S company KnipBio has used modified strains to produce KnipBio Meal, a high-quality feed protein comparable to fishmeal, from methanol. 

Wu said it is crucial that the physiological functions and nutritional value of methanol protein is improved and the market for functional proteins derived from it is expanded.

"That could further reduce production costs and increase the value of methanol protein, promoting its large-scale production," Wu said in a Science and Technology Daily report.

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