Literature Review Blog I

Title: Advanced biofuel production in microbes

1. What is the study’s objective/hypothesis/question?

The study looked in to the recent developments relating to the production of biofuels by microorganisms. The metabolic engineering of Escherichia coli and Saccharomyces cerevisiae, both easy to control, were the two organisms whose genetic and regulatory processes were monitored for the production of such biofuels.

2. What is the rationale and relevance of the question? (i.e. why was the study done?)

This study was conducted as a response to the innovation following the US Energy Independence and Security Act of 2007 that called for the production of 36 billion gallons of renewable fuel by 2022.  While ethanol produced from starch is a strong forerunner in these developments, ethanol is corrosive and draws too much moisture from its surroundings to be an economically feasible primary fuel of the future.  Ethanol also only contains 70% of the energy content of gasoline.  Moving forward, biofuels created must be compatible with existing infrastructure (that currently deals with petroleum) and able to be produced to necessary scale.

3. What is the relevance of this topic/question to engineering? (i.e. is it urgent or essential reading for a civil/environmental engineer?)


This topic is essential to engineering due society’s dependence on fuel and the need for an alternative source.  The three primary fuels that need to be replaced by biosynthetic fuels are gasoline, diesel and jet fuel.  Just as evidence by the recent hurricane, our way of life is crippled when fuel becomes scarce, which will happen permanently if we do not reroute our ways.  Not only is the environmental challenge to create a worthwhile fuel that will provide the necessary energy, but the civil engineering challenge is making sure all of our existing infrastructure, including engines, storage facilities and distribution systems.  Seeing as this particular article was published in 2009 and we have not made the holistic effort to switch over to biofuels, this is not something that can be tabled for later—it is an issue that requires intense study, thought and implementation to the billions of people that rely on current fueling methods.

Figure 1. A) Example of E. coli plated. B) Example of S. cerevisiae plated.

4. What methodological approach (design, analysis, etc.) has been used? (i.e. what was done?)

This study was more of a review of research that has already been conducted and its primary goal was to culminate those findings into a common area and benchmark the successes/failures.  Breaking down findings by different methods of manipulating and producing advanced biofuels, it first explored a biosynthetic pathway for the production of isopropanol and butanol. Then, rerouting the process of amino acid development for medium and long chained alcohols were discussed. Advances in fatty acid metabolism were reviewed as fatty acid based biofuels and the other topics have physical properties similar to current petroleum fuels in that these new advanced biofuels may be used as a supplement to current supplies.  Using microorganisms were looked at and determined to be the only way to bring these advanced biofuels to appropriate production scale as these microbes speed up the processes and can be manipulated to move the pathways in the necessary direction to create the advanced biofuels.  Again, no real experiments were actually conducted; a summary of other proceedings was just compiled.

5. What were the results of the study? (i.e. what did the investigators find?)

The results concluded a few different things as many topics were addressed. First, re routing amino acid generation for the creation of medium chain alcohols was successful, but it does have a few drawbacks: primarily, it ends up with a mixture of unknown alcohols.  At first, this unknown seems like a problem, but since gasoline is indeed a mixture of alcohols this may just be a positive similarity. Fine tuning the experiments may result in the production of individual alcohols. E. coli and S. cerevisiae generated isoprenoid-based biofuels produce many terpene structures on which more research needs to be conducted to find out which terpene molecules will work best as fuel alternatives.  Fatty acid research has shown that one company has produced a biodiesel using E. coli microorganisms mostly.

6. What were the strengths & weaknesses of this study? Are the results valid? (i.e. its study design, appropriateness of the method(s), relevant study group, sufficient sample size, appropriate study conduct, data gathering, subject follow-up, influences of bias, method of analysis, discussion, currentness and comprehensiveness of the listed references)

One strength of this study was its ability to cross over and between different methods of biofuel production instead of concentrating on a single area.  The last paragraph even states that while no one method has been breaking down all the barriers, the combination of all of these breakthroughs is what makes the biofuel goal attainable.  If the entire study was relying on one particular path to get the job done, it would end on a bleak note.  A double-edged sword, one weakness of this study was focusing on the many arrays of biofuel production.  There was not a strong conclusion for any particular path in that it seemed more of a ‘pat on the back’ to all those who participated instead of a critical analysis about what needs to be done to get the ball rolling.

7. Do the conclusions follow logically from the design and results?

Based on the unchartered territory it aims to cover, it makes sense why there is still a ton of uncertainty despite all of these biofuel research engagements.  The investigators acknowledge that scientists are on the right path towards a future that produces and uses advanced biofuels in many different methods, provided it can be made economically feasible for mass consumption.

8. How do the results relate to current practice and how might they influence future practice? (i.e. what does the answer mean anyway? So what and who cares?)

The compilation of research basically concludes that more research needs to be done.  While all these different branches of biofuel production may be flourishing, not a single one is to the point that it can totally replace what the gasoline, diesel and jet fuel needs we have today.  While there is a firm confirmation that what has been generated so far is compatible with current infrastructure, the true test will be if such biofuels can be mass-produced to make sense economically.

References

Agne27. (2008, September 18). Micro plate of Saccharomyces cerevisiae used in winemaking [Photograph]. Retrieved from https://commons.wikimedia.org/wiki/File:Plate_of_Saccharomyces_cerevisiae.jpg

Joydeep. (2009, October 13). E. coli culture stricked in a petriplate [Photograph]. Retrieved from https://commons.wikimedia.org/wiki/File:Bacterial_culture.jpg

Peralta-Yahya, P. P. (2010). "Advanced biofuel production in microbes". Biotechnology Journal, 5(2), 147; 147-162; 162.