Scientists Identify New Enzyme in Lignin Pathway

An international collaboration of scientists has identified a new enzyme that has a major role in the biosynthetic pathway of lignin, providing a new opportunity to greatly increase the efficiency of conversion of biomass to biofuels.

Lignin is a tough polymer in plant cell walls that limits the access to cellulose trapped within the plant biomass. Prior to conversion of cellulose to glucose molecules which can be fermented into fuel, the lignin barrier has to be removed by means of a harsh and energy-consuming pretreatment process. Thus, plants with lower amount of lignin or with lignin that is easier to break down can be an advantage in biofuel production.

Scientists from VIB and Ghent University (Belgium), the University of Dundee (UK), the James Hutton Institute (UK) and the University of Wisconsin (USA) have identified the new enzyme in the lignin pathway as caffeoyl shikimate esterase (CSE). Using Arabidopsis thaliana plants, the team performed a functional analysis of CSE through a gene knock-out approach. Plants with knocked out cse gene exhibited 36 percent less lignin per gram of stem material.

The new study published online in Science Express also found an altered structure for the remaining lignin in the modified Arabidopsis plants. As a result, the direct conversion of cellulose to glucose from non-pretreated plant biomass increased four-fold in cse-deficient plants.

The new insights from this research can be used to screen natural populations of bioenergy crops for a non-functional cse gene or to genetically engineer the expression of cse in these crops.