With the intensification of the climate crisis, natural
disasters have become more frequent and more severe.
Heatwave events have increased by
0%, with temperatures rising by
0°C.
0% of floods are related to abnormal heavy rainfall.
Droughts are occurring more frequently, are more severe, and
last longer.
Every harvest season, the burning of straw generates a large amount of greenhouse gases and also causes smog.
The global annual production of crop straw amounts to as much as 0 billion tons, but 0% of it, approximately 0 billion tons, is disposed of through open-field burning.
The reason straw is often burned is that it contains a large amount of lignin, which is difficult to decompose. Lignin is one of the most abundant but underutilized resources in the world.
Because it is difficult to degrade, although lignin has a very high value, 98% is simply burned, and only 2% is fully utilized.
In order to alleviate this issue, we want to find an efficient way to utilize lignin.
Lignin contains a large number of benzene rings, and in natural metabolic pathways, lignin is often utilized by breaking open the benzene rings, which greatly reduces the application value of lignin.
However, we have found that currently, lignin can be depolymerized into vanillic acid monomers by combining electrochemical and biological methods. This preserves the benzene ring of lignin, allowing it to realize greater value.
After that, we found a natural metabolic pathway that can retain the benzene ring and convert branched acids into paracetamol. If these enzymes can catalyze similar vanillic acid to produce paracetamol, it would be possible to convert lignin into high-value substances.
Through experimental validation, we found that this pathway can indeed catalyze vanillic acid, but nhoA also catalyzes different intermediate products, leading to a decrease in yield. We performed interference and knockout on nhoA separately, and the yield significantly increased in the knockout group.
In order to further increase the yield, we attempted to introduce more efficient exogenous genes. Thus, we replaced MNX1 with ABH60 and nhoA with PANAT, which ultimately significantly increased the yield.
Finally, we need to adjust the entire metabolic pathway. We replaced the promoter of PANAT with the temperature-sensitive promoter I38, allowing the accumulation of intermediates, and under suitable conditions, we activate the promoter to produce paracetamol.