The stems of trees and many plants usually contain a large amount of lignin which is difficult to be decomposed, so the efficiency of using them to extract biofuels is greatly reduced. At present, people have discovered a bacteria called Rhodococcus, which has the ability to decompose lignin in wood and other plants. 
Lignin is a kind of oil-paper umbrella polymer material. So far, more than 95% of lignin is directly discharged into rivers or concentrated and burned, and few of them are used effectively.
 it is believed that Rhodococcus can be widely used in mostly discarded stalks, thereby greatly improving the utilization rate of biofuels.