Newfound fungus makes better biofuel

A new found fungus living in rainforest trees makes biofuel more efficiently than any other known method, researchers say.

In fact, it's so good at turning plant matter into fuel that researchers say their discovery calls into question the whole theory of how crude oil was made by nature in the first place.

While many crops and microbes can be combined to make biofuels — including the fungi that became infamous as jungle rot during WWII — the newfound fungus could greatly simplify the process, its discoverers claim. Researchers have suggested that billions of acres of fallow farmland could be used to grow the raw material of biofuels. But turning corn stalks or switchgrass into fuel is a painstaking process and the end product is expensive and not entirely friendly to the environment.

The fungus, which has been named Gliocladium roseum, stands out in the crowd.

"This is the only organism that has ever been shown to produce such an important combination of fuel substances," said researcher Gary Strobel from Montana State University. "The fungus can even make these diesel compounds from cellulose, which would make it a better source of biofuel than anything we use at the moment."

The fungus grows inside the Ulmo tree in the Patagonian rainforest in South America. "When we examined the gas composition of G.roseum, we were totally surprised to learn that it was making a plethora of hydrocarbons and hydrocarbon derivatives," the stuff of diesel, Strobel said. The fuel it produces has been dubbed "myco-diesel."

Cellulose, lignin and hemicellulose make up the cell walls in plants. They makes the stalks, sawdust and woodchip and cannot be digested by most living things. Some 400 million tons of this plant waste is produced ever year just from farmland, Strobel and his colleagues say. In current biofuel production, this waste is treated with enzymes called cellulases that turn the cellulose into sugar. Microbes then ferment this sugar into ethanol that can be used as a fuel.

If G.roseum can be used commercially to make fuel, a step could be skipped.

"We were very excited to discover that G.roseum can digest cellulose. Although the fungus makes less myco-diesel when it feeds on cellulose compared to sugars, new developments in fermentation technology and genetic manipulation could help improve the yield," Strobel explained. "In fact, the genes of the fungus are just as useful as the fungus itself in the development of new biofuels."

The discovery also questions assumptions about how fossil fuels are made.

"The accepted theory is that crude oil, which is used to make diesel, is formed from the remains of dead plants and animals that have been exposed to heat and pressure for millions of years," Strobel said. "If fungi like this are producing myco-diesel all over the rainforest, they may have contributed to the formation of fossil fuels.

Source:Msnbc

Fungus That Produces Biofuels From Plants

The fungus Trichoderma reesei optimally breaks down plants into simple sugars, the basic components of ethanol. The fungus's genome has recently been sequenced by researchers from the Architecture et fonction des macromolécules biologiques laboratory (CNRS/Université de la Méditerranée and Universite de Provence), working together with an American team. The results show that only a few genes are responsible for the fungus's enzymatic activity. They offer new avenues for the fabrication of second generation biofuels from plant waste.

The fungus Trichoderma reesei was discovered in the South Pacific during the Second World War, where it was damaging American military equipment and was defeating every attempt at protecting the equipment with cotton cloth. The fungus contains a number of enzymes, cellulases, with potent catalytic properties that break down plants.  It is considered to be the world’s most efficient fungus at breaking down the cellulose in plant cell walls into simple sugars, which it feeds on.

After fermentation, simple sugars can easily be transformed into biofuels such as ethanol. First generation agrofuels, made from grain or from beet, have certain limitations. Second generation biofuels, made from foresting and agricultural waste (tree cuttings, corn cobs, straw, etc.) do not have these limitations, as they complement pre-established agricultural activity, have a better CO₂  balance, et don’t interfere with the agro-alimentary cycle.  To produce these second generation biofuels, industrialists are looking to develop fungus strains capable of producing a cocktail of cellulases and hemicellulases at a concentration of 50 g/l. Trichoderma reesei is the choice organism for most projects in this field.

Bernard Henrissat’s glycogenomic team at the Architecture et fonction des macromolécules biologiques lab specializes in the study of enzymes which break down sugars.* In order to learn more about the incredible enzymatic activity of Trichoderma reesei, they assayed its genome.  They found that the fungus has an unexpectedly small number of genes encoding cellulases (hemicellulases and pectinases), many fewer in fact than in usually found in fungi capable of breaking down plant cell walls. Moreover, the fungus has no or very little enzymatic activity allowing the digestion of specific components in the cell wall.

This was first interpreted as bad news, but the limitations of this model organism are now being seen as something positive. The fungus’s enzyme cocktail lends itself to numerous genetic modifications, and researchers are looking into which other enzymes can be added to the fungus’s gene sequence in order to make it even more efficient at producing bioethanol.

*The laboratory has a perfected Carbohydrate-Active Enzymes (CAZy) database which describes a number of enzyme families which form and destroy bonds between sugars.

Source:Science  Daily