Extremophile Converts Fatty Acids Into Energy

Biological Strategy

Syntrophus aciditrophicus

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Chemically Break Down Organic Compounds

The vast majority of biochemical assembly and breakdown processes–even by the most complex organisms–occur within cells. In fact, cells are able to perform hundreds, even thousands of chemical transformations at the same time under life-friendly conditions (ambient temperature and pressure in an aqueous environment). Part of the reason that decomposition reactions (chemical breakdown) can occur under such mild conditions is because most often, they occur in a stepwise, enzyme-mediated fashion, sipping or releasing small amounts of energy at each step. For example, the breakdown of glucose to pyruvate–and the release of energy–occurs in the 10-step enzyme catalyzed process of glycolysis.

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Bacteria

Domain Bacteria (“small staff”): L. acidophilus, Staphylococcus

From inside of our own bodies to the deepest parts of the ocean, bacteria have adapted to almost every possible environment. All bacteria are unicellular, microscopic, and lack a membrane-bound nucleus and organelles, and come in three basic shapes: spherical (cocci), rod (bacilli), and spiral (spirilla). Some strains can be deadly, like Staphylococcus aureus (MRSA) while others, like Lactobacillus acidophilus, found in our intestinal microbiome, keep us healthy. Cyanobacteria, also known as blue green algae, caused the Great Oxidation Event 2.4 billion years ago, producing Earth’s first oxygenated atmosphere.

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Metabolic process of extremophile bacteria converts fatty acids into a variety of secondary compounds, including hydrogen, by running normal metabolism backwards.

“It survives on a food so unrewarding it needs help disposing of its waste. Eking out an existence only by turning the normal chemistry of life back to front, the bacterium Syntrophus aciditrophicus is one of the most extreme-living organisms known. Now its genome has been sequenced and is yielding clues as to how it survives. It might even help us make hydrogen from waste. Robert Gunsalus of the University of California, Los Angeles, and colleagues identified 3169 genes in Syntrophus. The bacterium performs a key part of the carbon cycle by breaking down fatty acids–used by almost no other organisms as an energy source. To do this, its genes stand normal energy-generation reactions on their head (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0610456104). In normal respiration, organic compounds are oxidised, and the electrons this liberates are used to drive the production of the energy-storage molecule ATP. In Syntrophus the electrons go the opposite way as the bacterium turns fatty acids into a variety of breakdown products that it feeds on, plus hydrogen and the chemical formate. It survives only with the ‘help’ of other bacteria that hoover up the hydrogen and formate–otherwise it could not feed. Understanding the bacterium’s metabolism will ‘hopefully make biohydrogen production a reality’, says Gunsalus.” (Hooper 2007: 12) from issue 2600 of New Scientist magazine, 21 April 2007, page 12)

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