Drive for creating synthetic biofuels is gaining momenta. In fact synthetic biology community is trying to use bacteria and yeast as platform to creat biofuels. To this end microbes can convert the simple fermentable sugar into ethanol or other products. Plants are naturally abundant source of renewable biofuel and as matter of fact most of fossil fuel such as oil and gas have been formed from the anaerobic decomposition of prehistoric plants and animals. Formation of fossil fuel is a very slow process and it takes millions of years to form. This is why fossil fuels are non-renewable resources and our current consumption rate is faster than fossil fuel formation process. One of the main reasons for the slow fossil fuel formation is the structure of plant cell wall which is composed of highly cross-linked heterogeneous polysaccharidic matrix. This complex matrix resist the enzymatic hydrolysis or saccharification, a key process which converts polysaccharides in the plant cell wall into fermentable sugars such as glucose and fructose. Although enzymatic hydrolysis is most promising and environmentally friendly technology available to extract biomass associated with cell walls, industries have mainly relied on alternative approaches such as thermochemical pretreatments coupled with mechanical disruption which can represent up to 30% of the cost of biofuel manufacturing. By genetically modifying plant cell walls to increase the efficiency of enzymatic saccharification one can expect a major cost cutting related to pretreatments. In recent issues of journal PNAS Vincenzo Lionetti et al. report that genetically modified Arabidopsis plants show improved enzymatic saccharification efficiency. In this study authors investigated

whether the structure of pectin that embeds the cellulose-hemicellulose network affects the exposure of cellulose to enzymes and consequently the process of saccharification. Reduction of de-methyl-esterified homogalacturonan (HGA) in Arabidopsis plants through the expression of a fungal polygalacturonase (PG) or an inhibitor of pectin methylesterase (PMEI) increased the efficiency of enzymatic saccharification.

By expressing fungal polygalacturonase (PG) in tobacco plants and pectin methylesterase (PMEI) in wheet plants they were able to achive similr kind of results. Further they concluded that

PGs and, more in general, other HGA-degrading enzymes such as pectate lyases may be used to reduce the acidic HGA content in crop plants as well as in energy plants and make them a better substrate for the production of biofuel and other commercial products.