ICB Research May Lead to Clean Power Generation that Offsets the Cost of Water Treatment

Friday, February 17, 2017
Co-authors Nathan Kirchhofer, Zachary Rengert and Guillermo Bazan. (Photo credit: Sonia Fernandez)

ICB project leader and lead author of a study that was recently published in the journal Chem, Guillermo Bazan and his team of researchers at UCSB chemically modified the bacteria Shewanella oneidensis MR-1 to increase its energy production capabilities. This research could lead to another way for wastewater treatment plants to not only decontaminate water but to also generate some of their own power without many of the current limitations.

The bacteria that inspired this study, Shewanella oneidensis MR-1, live in oxygen-free environments and can breathe in metal minerals and electrodes—instead of air—via current-conducting proteins in their cell membranes. Most bacterial species, however, do not have such proteins and therefore naturally do not produce current.

To better harness the ability of the bacterium's cells to produce energy as part of their metabolism, the research team developed an iron-containing synthetic molecule called DSFO+, which modifies these cell membranes but can still conduct electrons.

Tested in two mutant strains of Shewanella, the team found that DSFO+ could not only completely replace the natural current-conducting proteins, but do their job more efficiently, boosting the power that the microbe generated.

"The protein replacement molecule that we constructed modifies the cell membrane so that it facilitates respiration by electron delivery to the membrane surface," says Guillermo Bazan, "It's a power-generating trick that gives us an opportunity to look into the behavior of microbial species in a way that didn't exist before."

In addition to being more efficient at generating energy, the DSFO+ could also act as a kind of power adapter between the electricity produced and the manmade systems that could harvest it. In their natural state, bacteria like Shewanella cannot electrically communicate with an electrode, but this synthetic molecule could open up the possibility. Eventually, the microbes could be used to not only break down contaminants in wastewater, but in the process generate enough electricity to recoup some of the cost of that water treatment.

In the meantime, the researchers are hoping to use the modified bacteria to study the internal processes of the species, which could lead to further breakthroughs and applications down the track.

"One idea is removing electrons, which is common and easily performed," says Bazan. "But what happens if we provide electrons to carry out chemical reactions? Can we also monitor the health of that microorganism by its electronic signatures? If we put a drug in the organism, how does that impact its metabolism? If we stress the microbe, how does it breathe? If it's in a community of microorganisms, are they sending electronic signatures to let each other know what's going on? Can we intercept that? Can we record that? These possibilities are becoming viable now and open up fundamentally new avenues of research."