TU-103 is the first bacterial strain found in nature (not genetically engineered) to produce butanol directly from cellulose. It is also the only strain yet found that can grow in the presence of oxygen. Keeping bacterial fermentation chambers air tight makes other strains more expensive to work with.
Cellulose biofuels have advantages over ethanol from corn and sugar cane. It doesn’t compete for crop land, since cellulose containing plants can be grown on lands where other crops won’t grow.
Butanol is also superior to ethanol in several ways. It can be used without modifying automobile engines, and is less corrosive. Butanol also contains more energy than ethanol, so cars fueled by butanol won’t lose miles-per-gallon, as they do with ethanol and ethanol blends like E85.