if cellulase microbes get loose

[mattw]

Because cellulosic ethanol would be such a great source of fuel if it can be produced economically, people are working on creating cheaper more effective "cellulases". If the microbes that create these improved enzymes get loose, could they eat all of Earth's plants?

[canalon]

Right now they exist, but they do not seem to do much damage.
There are many things that are likely to prevent massive advantage of those enzyme:
- The access they need to cellulose (plants need to be chewed rather than just standing there)
- Temperature optimum
- Ability of the bacteria to survive outside its host/fermentor

But all that could evolve, and why not? Then at least we would die drowning in ethanol, I can imagine worse than a gigantic binge death

[skeptic]

This is one of the horror stories occasionally entered into by anti-GM activists. Sadly for them, the scenario has been tested. GM bacteria with enhanced cellulasic activity have been made, and proven in the laboratory. However, when exposed to 'natural' conditions, they tend to die out very quickly. Those enhanced cellulase properties are all very well under man-made conditions, but make the organisms less competitive in the natural world.