Solar Powered Microbes Manufacture Biofuels

esocid alerts us to news that scientists from the University of Texas at Austin have created a microbe capable of making cellulose, which can then be turned into ethanol. The bacteria use sunlight as an energy source, and the cellulose can be harvested without destroying them. Quoting: "The new cyanobacteria produce a relatively pure, gel-like form of cellulose that can be broken down easily into glucose. 'The problem with cellulose harvested from plants is that it's difficult to break down because it's highly crystalline and mixed with lignins [for structure] and other compounds,' Nobles says. He was surprised to discover that the cyanobacteria also secrete large amounts of glucose or sucrose, sugars that can be directly harvested from the organisms."

Comments

Re:Precision in Reporting ...

[cosmicaug]

It looks like they they need to control the simple sugar secretion problem. This is not only an organism which wastes energy (from its "perspective") for no good reason by making cellulose but also an organism which is considerate enough to potential competitors to give them an easy to use energy source in the form of simple sugars.

The former (the part we want) makes the organism weak but might be manageable. The latter, makes the organism "stupid" and, if it produces large enough quantities of simple sugars to sustain high densities of other microbes feasting on simple sugars, suicidal since secondary metabolites (or simply overwhelmingly high numbers of competitors) will probably make a population of this organism unsustainable.

Re:Very large surface area needed

[budgenator]

Corn for just ethanol is a bad idea, but corn pressed to remove the oil for biodiesel,
sugar removed for fermentation to ethanol
the stover used for cellulose conversion,
and the high protein distiller's dried grain fed back to cattle for food production, not so bad.

Not necessarily suicidal

[Moraelin]

It's not necessarily suicidal.

Cyanobacter are routinely part of lichens, which are a very weird mix of fungi and bacteria capable of photosynthesis. The fungi form a matrix in which the bacteria are trapped, and help collect minerals and moisture for the trapped bacteria.

The arrangement isn't entirely mutually beneficial, from the point of view of the individual bacteria, but from a propagating-the-genes point of view (which in evolution is the only one that matters at all) it does allow the bacteria to live and multiply in some places where it otherwise could not.

And the fungi aren't doing it as some kind of act of kindness, either: fungi can't do photosynthesis on their own, so those lichens growing on rocks and whatnot, well, would die if noone in that arrangement provided food for the fungi too. That's the bacteria's contribution there: those sugars.

At any rate, it's sorta like being inside a living test tube full of nutrients and water. If you don't produce an excess of sugars, the test tube dies. Clearly there's a survival advantage in avoiding that.

From another point of view, fungi are nasty critters, which can only live on organic matter produced by someone else. It may be parasitic (they take other cells apart and eat them) or they can live on dead matter, but nevertheless they absolutely need someone else to manufacture those nutrients for them. Most of those in lichens are a highly specialized and adapted form of parasite. They don't just live off the nutrients that the bacteria excrete, but actually poke the bacteria with tiny filaments and suck the nutrients right out of the living cell. The trapped bacteria are routinely killed in the process, but the colony survives by just allowing them to multiply faster than they're killed.

Again, it's a survival advantage to be able to produce enough of an excess of nutrients, so you can survive (and make enough of a reserve to divide too) even with 3-4 fungal cells around you, all living off you.