New Biofuel-Producing Bacteria Discovered

Scientists from the University of Maryland will report in the Journal of Theoretical Biology that they have isolated several different strains of bacteria that make high concentrations of biofuels from cellulosic biomass or from carbon dioxide and hydrogen gas.

The authors isolated bacteria that make high concentrations of alcohols including ethanol and 1-butanol, and other strains that make hydrocarbons, like hexane and octane.  These compounds are similar to components already found in gasoline.

Although the Department of Energy and many investors have invested millions of dollars trying to genetically engineer organisms like these, the scientists from Maryland led by UM professor Rick Korn say that such organisms are already common in nature. The reason the fuel doesn’t accumulate in natural environments is because it is more thermodynamically favorable to make other products.  When the products are made in nature, they are converted to other products by different organisms.

Using mathematical models of natural ecosystems incorporating the laws of thermodynamics, the authors identified conditions that favor production of desired fuels.  When they applied those conditions to mixed cultures of organisms taken from the rumen, or first stomach chamber of a cow, the desired fuel-producing organisms thrived and were enriched in the culture.  Eventually, using those favorable conditions, the fuel-producing bacteria were isolated.

The authors believe the research represents a paradigm shift for industrial microbiology because it shows how to isolate microorganisms based on the products they make as well as the substrates they use.  Previously, microbiologists would have isolated bacteria that grow on a certain substrate, for example cellulosic biomass, and then test to see what products they made.  However, they usually would not make fuels because the conditions of the culture tended to mimic the conditions of the natural environment, and therefore fuel production was not thermodynamically favorable.  In the authors approach, they use conditions to select for organisms that use the biomass to make certain products, like alcohols or hydrocarbons.

The organisms may be used to produce fuels directly from biomass, including cellulosic biomass.  When all of the steps of digestion and fermentation are combined, it is called consolidated bioprocessing.  The organisms available for consolidated bioprocessing to produce cellulosic ethanol do not produce high concentrations of the ethanol, and therefore it isn’t cost effective to use them.   The organisms the authors isolated were tolerant to as much as 6 to 10% ethanol.

The organisms may also be used to produce fuels from carbon dioxide and hydrogen.  Some companies such as Ineos Bio, Lanzatech, Coskata, and Oakbio are developing methods to produce fuels from carbon dioxide or carbon monoxide and hydrogen gas.  Again, a major limitation is the low concentration of alcohols produced.  The organisms reported in the article are tolerant to high concentrations of ethanol or butanol.

The authors own two US patents and several US and European patent applications on the methods.  The article will be titled, “Using the second law of thermodynamics for enrichment and isolation of microorganisms to produce fuel alcohols or hydrocarbons”, and it has been accepted for publication in the Journal of Theoretical Biology.rtnership recently formed to provide ethanol and fuel storage, terminal and transportation services by owning, operating, developing and acquiring ethanol and fuel storage tanks, terminals, transportation assets and other related assets and businesses.

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