Qteros microbe achieves unprecedented ethanol outputs

By Lisa Gibson and Craig A. Johnson | September 15, 2009
Massachusetts-based Qteros recently announced it has achieved unprecedented lab results in the performance of its Q Microbe complete cellulosic conversion process. The microbe can achieve outputs of 70 grams of ethanol per liter of fermentation broth, or 9 percent ethanol by volume, in a single-step process on industrially pretreated cellulosic biomass feedstocks, according to the company. The threshold for commercial production of cellulosic ethanol is considered to be 50 grams per liter. Qteros said this breakthrough makes its process the most economic to date.

According to Qteros, "The Q Microbe breaks down a wide variety of plant materials, including corn residues, cane bagasse, woody biomass, cellulose waste and more. It produces prodigious amounts of ethanol by generating its own enzymes and then fermenting the C5 and C6 sugars. The microbe can be engineered to optimize ethanol output from a specific plant material, increasing net energy yield for the whole system. It is the yeast' component of the conventional bioconversion process plus the enzyme component, all in one."

The Q Microbe (Clostridium phytofermentans) was discovered approximately 12 years ago in Massachusetts' Quabbin Reservoir by a University of Massachusetts research team led by Susan Leschine, a microbiologist at the university. It was collected in a sample for another survey and its potential was not realized until about eight years later.

"The discovery was almost accidental," Leschine said. The lab had been testing different microbes when someone inadvertently put too much paper in with the microbial media. Not expecting a positive result, the team tested the media and discovered the microbe was capable of producing high levels of ethanol from raw biomass.

"The major impediment to producing cellulosic ethanol is cost," Leschine said. "The Q Microbe minimizes pretreatment while optimizing cost. Other processes use diluted acids or high-temperature pretreatments, which take a lot of additional energy to perform."

Leschine said the goal is to develop a microbe that can process feedstocks with little or no pretreatment. "An ideal situation is one where a producer could put large, untreated biomass into a digester and have the microbe do all of the work," she said.

In the past year, the Qteros scale-up team has increased ethanol concentrations by a factor of five in the solution that's produced when the Q Microbe hydrolyzes and liquefies biomass, according to president and CEO William Frey. Even though it has reached world-class outputs with a non-genetically engineered strain of the microbe, the company expects to make further improvements by taking advantage of ongoing efforts in molecular genetics and strain development.

"We knew from the beginning that the Q Microbe was an extraordinary microorganism," Leschine said. "These results confirm what we predicted: Qteros and the Q Microbe can make cellulosic ethanol a commercial reality."