Even inside the human body, there are mysteries left to uncover. For example, scientists just discovered that bacteria in the stomach can actually produce electricity.

For those who are trying to create sustainable, living batteries out of microbes, these findings are a significant step in achieving their goal.

Gut Bacteria With A Spark

In a study available online and set for publication in the Oct. 4 issue of the journal Nature, researchers reveal that hundreds of gut bacteria are able to generate electricity using a different technique than other electrogenic bacteria.

Some of the gut bacteria found to produce electricity include Listeria monocytogenes, which causes diarrhea; Clostridium perfringens, which causes gangrene; Enterococcus faecalis, which causes hospital-acquired infections; and various disease-causing streptococcus bacteria.

Many are probiotics, while a handful are found to ferment yogurt.

It's not the first time that bacteria have been found to be able to produce electricity. It's not even the first time that bacteria inside the body have been shown to be electrogenic. However, even scientists are amazed that they missed so many major ones in the stomach.

"The fact that so many bugs that interact with humans, either as pathogens or in probiotics or in our microbiota or involved in fermentation of human products, are electrogenic — that had been missed before," Dan Portnoy, a University of California, Berkeley professor, says in a press release from the university.

He adds that this could lead to more information about how bacteria infect humans as well as how it could help promote a healthy gut.

A Closer Look At The Electrogenic Bacteria

According to UC Berkeley, bacteria primarily produce electricity to remove electrons that crop up from metabolism as well as to support energy production. While plants and animals use oxygen for their metabolic process, bacteria found in places without oxygen — such as the gut — must use other elements.

Electrogenic bacteria in mines and lakes have been found to utilize minerals such as iron or manganese in a complex series of special chemical reactions known as the extracellular electron transfer chain carrying the electrons out as an electrical current.

On the other hand, the newly discovered electricity-producing gut bacteria use a vitamin B2 derivative called flavin in a much simpler transfer system. It appears that these bacteria only use the extracellular electron transfer chain when it's necessary and the oxygen levels are low, since in this case, their cell structure and environment make it cost effective to move electrons out of the cell.

"Thus, we think that the conventionally studied mineral-respiring bacteria are using extracellular electron transfer because it is crucial for survival, whereas these newly identified bacteria are using it because it is 'easy,'" Sam Light, first author and a postdoctoral fellow, concludes.