Extracto que contiene Jawsamicina. Crédito: Pablo Morales-Cruz
Los aviones son indispensables en la era moderna para transportar personas, entregar bienes y realizar operaciones militares, pero los combustibles a base de petróleo que los impulsan escasean. Los científicos ahora han descubierto una forma de generar combustible alternativo para aviones mediante la recolección de una molécula de carbono inusual producida por el proceso metabólico de las bacterias que se encuentran comúnmente en el suelo. La investigación, realizada por científicos del Lawrence Berkeley Lab, se publicó recientemente en la revista Joule.
“En química, todo lo que necesita energía para fabricarse libera energía cuando se rompe”, dice el autor principal Pablo Cruz-Morales, microbiólogo de DTU Biosustain, parte de la Universidad Técnica de Dinamarca. Cuando se enciende el combustible para aviones a base de petróleo, se libera una enorme cantidad de energía. Los científicos del Laboratorio Keasling del Laboratorio Lawrence Berkeley creían que tenía que haber una manera de replicar esto sin tener que esperar millones de años para que se formaran nuevos combustibles fósiles.
Una idea explosiva
Para ver si podía sintetizar una molécula delicada que tiene el potencial de producir mucha energía, Jay Keasling, ingeniero químico de[{” attribute=””>University of California, Berkeley, approached Cruz-Morales, who was a postdoctoral researcher in his lab at the time. “Keasling told me: it’s gonna be an explosive idea,” says Cruz-Morales.
The common bacteria streptomyces which makes the cyclopropane-containing molecules. Credit: Pablo Morales-Cruz
Keasling wanted to recreate a molecule called Jawsamycin, which is named after the movie “Jaws” because of its bite-like indentations. It is generated by the common bacteria streptomyces, an organism that Cruz-Morales had worked with in the past.
“The recipe already exists in nature,” says Cruz-Morales. The jagged molecule is produced by native metabolism of the bacteria as they munch away on glucose. “As they eat sugar or amino acids, they break them down and convert them into building blocks for carbon-to-carbon bonds,” he says. “You make fat in your body in the same way, with the same chemistry, but this bacterial process has some very interesting twists.”
These twists, which give the molecules their explosive properties, are the incorporation of cyclopropane rings – rings of three carbon atoms arranged in a triangular shape. “If you have bonds that are at a normal angle, an open chain of carbons, the carbons can be flexible and they get comfortable,” explains Cruz-Morales. “Let’s say you make them into a ring of six carbons – they can still move and dance a little bit. But the triangle shape makes the bonds bend, and that tension requires energy to make.”
After careful analysis, the research team determined that the enzymes that were responsible for the construction of these high-energy cyclopropane molecules were polyketide synthases. “Polyketide synthases are the ultimate biological tool to make organic chemistry,” says Cruz-Morales.
Making Fuel With Biology
Cruz-Morales explains that the fuel produced by the bacteria would work a lot like biodiesel. It would need to be treated so that it could ignite at a lower temperature than the temperature needed to burn a fatty acid. However, when ignited, it would be powerful enough to send a rocket into space. “If we can make this fuel with biology there’s no excuses to make it with oil,” says Cruz-Morales. “It opens the possibility of making it sustainable.”
In the future, Cruz-Morales hopes that he and the team of Department of Energy researchers who worked on the project will be able to scale up this process so that their alternative fuel could actually be used in aircraft. “The problem right now is that fossil fuels are subsidized,” says Cruz-Morales. “This is something that is not only related to the technology, but the geopolitical and socio-political constitution of the planet right now. You can see this as a preparation for the moment because we are going to run out of fossil fuels, and there’s going to be a point, not far from now, when we will need alternative solutions.”
Reference: “Biosynthesis of polycyclopropanated high energy biofuels” by Pablo Cruz-Morales, Kevin Yin, Alexander Landera, John R. Cort, Robert P. Young, Jennifer E. Kyle, Robert Bertrand, Anthony T. Iavarone, Suneil Acharya, Aidan Cowan, Yan Chen, Jennifer W. Gin, Corinne D. Scown, Christopher J. Petzold, Carolina Araujo-Barcelos, Eric Sundstrom, Anthe George, Yuzhong Liu, Sarah Klass, Alberto A. Nava and Jay D. Keasling, 30 June 2022, Joule.
DOI: 10.1016/j.joule.2022.05.011
