Hugh Bollinger / Friday, July 15, 2011

Hot bugs

Enzymes are bio-molecules produced in the cells of all fungi, bacteria, yeasts, animals, and plants. They act as catalysts used in everything from laundry detergents, to meat tenderizers, from brewing beer, producing cheese, and digesting cellulose. Enzymes are essential to natural recycling functions of ecosystems and have become part of commercial processes more numerous than can be easily listed. They are biochemical workhorses due to the elegant specificity of their catalytic interactions. Enzyme uses expand daily and a new discovery could put them to work in an industrial one well beyond their traditional food, fermentation, and environmental clean-up applications and into alternative energy production-- possibly their biggest use so far imagined. [caption id="attachment_5655" align="aligncenter" width="300" caption="Specific site of enzyme action in purple (source: Wikipedia)"]

[/caption] Major efforts are underway worldwide to identify new enzymes. The most productive locales for discovering new microbial candidates for enzyme screening are extreme environments such as hot springs, beneath Antarctic glaciers, or living in super-arid desert soils. Organisms that can tolerate such extremely high or low temperatures or highly toxic soils are known as extremophiles. [caption id="attachment_5661" align="aligncenter" width="800" caption="Grand Prismatic Spring, Yellowston NP (source: National Park Service)"]

[/caption] Investigators at UC Berkeley and the University of Maryland have now identified a microbe from a Nevada hot spring that happily eats plant material-- cellulose --at temperatures near the boiling point of water. This discovery opens the door to industrial scale cellulosic biomass conversion for ethanol manufacturers. Cellulosic ethanol is an exciting but still emerging alternative energy resource. It's commercial development wouldn't compromise corn supplies as a food stock for ethanol production. Thus far, the costs of cellulosic biomass conversion and the effectiveness of current enzymes have been prime limiting factors to its wide-scale implementation. The new hyper-thermophilic microbe-- discovered in a 203 degree Fahrenheit geothermal pool --is only the second member of the ancient microbial group, the Archaea, known to grow by digesting cellulose above 175F. It lives off on decaying plant matter that sinks to the bottom of the hot spring by employing a highly heat tolerant form of cellulase. Its enzyme is so stable that it works in hot solutions that could easily digest biological feedstocks and liberate cellulose for ethanol fermentation. The lead researcher, Doug Clark says: "The new cellulase may actually work at too high a temperature for some processes." However, the discovery allows protein engineers the opportunity to develop a remodeled version of the molecule optimized to catalyze at lower temperatures but maintaining the robust structural stability found in the wild organism. Mother Nature has always been creative in applying the evolutionary tool of natural selection to produce amazing new and diverse life forms. With these "hot bugs", she has proven to be potentially a fine industrial and alternative energy engineer as well. WHB

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Tags: alternative energy extremophiles cellulase cellulosic ethanol energy efficiency enzymes ethanol Yellowstone National Park

Hot bugs

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