Tungsten is exceptionally rare in biological systems. Thus, it came as a huge surprise to Michael Adams, PhD., and his collaborators when they discovered it in what appeared to be a novel enzyme in the hot spring-inhabiting bacterium, Caldicellulosiruptor bescii. The researchers hypothesized that this new tungstoenzyme plays a key role in C. bescii‘s primary metabolism, and its ability to convert plant biomass to simple fermentable sugars. This discovery could ultimately lead to commercially viable conversion of cellulosic (woody) biomass to fuels and chemical feedstocks, which could substantially reduce greenhouse emissions. The research is published 14 August in Applied and Environmental Microbiology, a journal of the American Society for Microbiology.
Cellulosic biomass’ advantage as a feedstock for fuel and chemical production is that it need not compete with food production for land. Its big challenge is that cellulose is highly resistant to enzymatic degradation. To date, most efforts to convert it to useful chemicals have involved energetically expensive pretreatment.
Avoiding pretreatment would boost commercial viability. To this end, the investigators, members of the Department of Energy’s BioEnergy Science Center, have been focusing on Caldicellulosiruptor species (the name of the genus means “hot cellulose-breakers,”), which inhabit volcanic hot springs around the world.
While the putative novel tungstoenzyme Adams et al. discovered looked fairly promising, Adams, who is Distinguished Research Professor of Biochemistry & Molecular Biology at the University of Georgia, Athens is quick to assert that a likely sequence does not constitute proof of function. In fact, “I would have predicted…