Production of high protein straw feed by recombinant Saccharomyces cerevisiae

In the fields, we see:

After picking the corn, a large amount of straw accumulates in the farmland.According to survey statistics, in 2019, the theoretical amount of straw resources was 840 million tons, and the recoverable resources were about 700 million tons.

Are they really useless?

Visiting the breeding farmers, they said:

“As food prices are rising, so the price of food and feed is rising. Our cost pressure is also increasing.”

How can we help them?

We propose a bold idea of combining them to —— to produce low-price feed from straw.

But is this really possible?

So,

we created the Wuhan-Hubei-China team and worked to solve this problem with a synthetic biology approach.

Yeast single-cell protein (SCP, single cell protein) protein content is close to fish meal, and is rich in a variety of essential amino acids, is a very promising feed protein. So we chose it as the chassis organism.

To enable the yeast to use cellulose:

We fused the three cellulose genes (bg, cbh, eg) into a fusion fragment and constructed the fusion gene plasmid.

The constructed plasmid was transferred into yeast, allowing it to acquire the ability to decompose cellulose.

Note that there are also many xylancans in straw, we chose to use error-PCR to mutate and select strains that can decompose xylan efficiently.

The selected strains expressed xylanase with high enzyme viability in the cells.

After crushing the cells, we isolated the active xylanase proteins using a chromatography column.After adding straw, xylan was decomposed into xylose.

We also made promoter optimization in the strains imported into the xylose isomerase gene. For the yeast to use both glucose and xylose.

Under various optimized interactions, the straw can finally be converted into high-protein feed.