Heard the buzz?

University of Iowa researchers identify caffeine-consuming bacterium

As it turns out, humans aren't the only organisms that turn to caffeine for a pick-me-up. University of Iowa scientists have identified four different bacteria that actually can live on caffeine.

One of them, known as Pseudomonas putida CBB5, was found in a flowerbed outside a UI research laboratory. The research team says the discovery—and the new understanding of how the process works—could in the future allow scientists to convert waste from leftover coffee, tea, and even chocolate into useful substances, like pharmaceuticals, animal feed, or biofuels.

Previous studies have also discovered caffeine-degrading bacteria, but the UI team took the research one step further. They identified the gene sequence that enables the bacterium to break down the caffeine compound in nature.

Caffeine is found naturally in more than 60 plants and is composed of carbon, hydrogen, nitrogen, and oxygen. Its molecular structure features three clusters of carbon and hydrogen atoms known as methyl groups, enabling caffeine to resist degradation by most bacteria.

Led by UI chemical and biochemical engineering doctoral student Ryan Summers, the study found that Pseudomonas putida CBB5 uses four newly discovered digestive proteins to break caffeine down into xanthine and then to carbon dioxide and ammonia. It removes the methyl groups from the molecule (a process called N-demethylation), allowing the bacteria to feed on the nitrogen atoms in the interior of the molecule (xanthine).

The caffeine digestive proteins from CBB5 can be used to convert caffeine into building blocks for drugs used to treat asthma, improve blood flow, and stabilize heart arrhythmias.

"With one or two methyl groups removed, the remainder of the molecule can be used as the base for a number of pharmaceuticals," Summers says. "You basically use the new genes and enzymes that could take something we have a lot of—like caffeine—and make drugs that are typically very expensive. And that process could lower the costs for people who need them."

Summers says the bacterium's digestive proteins could also be used to remove caffeine and related compounds from large amounts of waste generated from coffee and tea processing, which pollute the environment. The decaffeinated waste from these industries could be used for animal feed, or for production of transportation fuel, especially in areas where corn (for ethanol) is scarce.