Wednesday, March 02, 2011

A Faster Butanol Bio-Synthesis from UC Berkeley Chemists

University of California, Berkeley, chemists have engineered bacteria to churn out a gasoline-like biofuel at about 10 times the rate of competing microbes, a breakthrough that could soon provide an affordable and “green” transportation fuel...The advance is reported in this week’s issue of the journal Nature Chemical Biology _UCBerkeley
Butanol is far superior to ethanol as either a fuel additive in gasoline and diesel, or as a drop-in substitute for gasoline in modern engines. Up until now it has been too expensive to ferment butanol from sugars, but UC Berkeley's gene-modified chimeric E. Coli may be the beginning of a new butanol age. By transplanting genes from Clostridium acetobutylicum, Treponema denticola and Ralstonia eutrophus, into E. Coli, the Berkeley scientists are helping lay the groundwork for a brave new microbial world of frankenstein fuel factories.
The new genetically altered E. coli produced nearly five grams of n-buranol per liter, about the same as the native Clostridium and one-third the production of the best genetically altered Clostridium, but about 10 times better than current industrial microbe systems.

“We are in a host that is easier to work with, and we have a chance to make it even better,” Chang said. “We are reaching yields where, if we could make two to three times more, we could probably start to think about designing an industrial process around it.”_UCBerkeley_via_GCC

Synthetic biology approaches to fuels production, such as described in the article above, have a bright future -- as oil prices tend to rise by fits and starts over the years. But synthetic biology is in a race with nano-technological abiotic approaches to catalysis which may prove far more robust in the long run.

Butanol creates a difficult growing environment for many micro-organisms. It is difficult to engineer an organism capable of tolerating significant levels of butanol in solution. Consequently, researchers must develop strains of microbes capable of fast synthesis -- along with the rapid means for separating the butanol product from the microbial fermentation solution, for the sake of the microbes' survival.

It is unclear whether the chimeric synth-bio approach will be superior to multi-microbial "production lines" -- using different species to perform the different steps of the synthesis. In general, the fewer separate production steps, the less expensive the setup.

Microbes recreate themselves at exponential rates under proper conditions. This makes microbial fermentation self-sustaining in terms of microbes.

Abiotic catalysts, on the other hand, must be mined, refined, and manufactured. It becomes an economic race between artificially controlled natural processes and increasingly automated industrial processes. In the long run, the most productive, most robust, and most economic catalyst will win out.

More: Here is a method of creating butanol from algae, developed by scientists at the University of Arkansas. The method involves so many steps, however that it is not likely to ever become economical in its present form. All the same, the U. Arkansas approach does illustrate one approach to the use of open pond algae as a biomass feedstock for producing advanced biofuels. For that reason alone, it is worth mentioning.



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