Microbial remedies target chemical threats in the environment

ASU researchers describe how microbial life can clean up locations contaminated with two chlorinated chemicals, TCE and perchlorate

November 17, 2020

Across America, hazardous waste sites pose an ongoing threat to human and environmental health. The most severe cases are known as Superfund sites, of which over 1,000 currently exist. Some 50 million Americans live within 3 miles of one of these zones, potentially placing them at increased risk for cancer and other serious diseases.

While decontamination of such sites is a public health priority, the technical challenges are daunting. Of particular concern are a pair of chlorinated chemicals: trichloroethylene, known as TCE, and perchlorate. TCE was widely used as a degreasing agent and perchlorate is used in the manufacture of propellants. Due to the widespread reliance on these chemicals in the past and their improper disposal, they have often found their way into the environment, posing significant risks to human health and surrounding ecosystems. Severely contaminated areas — known as Superfund sites — number over 1,000 in the U.S. alone. A powerful technique using microbial life to clean up locations contaminated with two chlorinated chemicals, TCE and perchlorate, is described in new research. Download Full Image

Bioremediation for the removal of these highly toxic chemicals, especially when they are present in mixtures, has long been a challenge for scientists. Chlorinated chemicals stubbornly persist in the environment, sometimes contaminating drinking water systems.

In a new study, researchers at Arizona State University's Biodesign Swette Center for Environmental Biotechnology explored new ways to rid the environment of these co-occurring toxic chemicals. To accomplish this, Fe0 (known as zero valent iron) in combination with microbial cultures containing an unusual microbe known as Dehalococcoides mccartyi were added to soil and groundwater samples from a contaminated Superfund site in Goodyear, Arizona. The contaminated site had formerly been involved in defense and aerospace manufacturing.

The researchers describe how Dehalococcoides bacteria can act in synergy with Fe0. The new study describes the conditions under which Fe0, Dehalococcoides and other bacteria can effectively convert TCE and perchlorate to benign or less-toxic end products of microbial biodegradation, (e.g., ethene).

The study appears in the current issue of the journal Environmental Science & Technology.

Critically, the technique prevents the TCE degradation reaction from stalling midway through the process. When this happens, a pair of chemicals, cis-DCE and vinyl chloride are produced, instead of ethene. This would be bad news for the environment, as vinyl chloride is recognized as a highly potent carcinogen.

man's portrait

Srivatsan Mohana Rangan

Instead, by using low concentrations of aged Fe0 along with Dehalococcoides, a complete reduction of TCE and perchlorate to harmless ethene and chloride ions was achieved. The study also demonstrated that high concentrations of Fe0 inhibited TCE and perchlorate reduction while ferrous iron (Fe2+), an oxidation product of Fe0, significantly slowed down TCE reduction reaction to ethene.

“Usually, polluted environments contain more than one toxic contaminant, yet, we have limited information for managing environments with multiple contaminants,” said Srivatsan Mohana Rangan, lead author of the new study.

“The synergies between microbiological and abiotic reactions can help achieve successful remediation of multiple contaminants simultaneously in a shorter time frame. Our study using microbial cultures with a chemical reductant, zero valent iron, demonstrates scenarios for successful remediation of TCE and perchlorate, but also underscores scenarios which can exacerbate environmental contamination, by generating carcinogenic chemicals.”

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Anca Delgado

“We hope this study will help inform remedial design at Phoenix Goodyear Airport North Superfund Site and other contaminated environments where chemical reductants such as Fe0 are used to promote long-term and sustained microbial activities in the soil and groundwater,” said Anca Delgado, co-author of the new study.

In addition to her Biodesign appointment, Delgado is an assistant professor at ASU’s School of Sustainable Engineering and the Built Environment.

The research findings pave the way for advanced microbial solutions to address contamination by chlorinated chemicals at Superfund sites across the country.

Richard Harth

Science writer, Biodesign Institute at ASU


Technology enables historic international connection for ASU students in 'remote' piano master class

November 17, 2020

When distance learning involves overseas students studying music, a Zoom call isn’t quite good enough. So, on Oct. 22, Cathal Breslin, assistant professor of piano in Arizona State University's School of Music, Dance and Theatre and a Yamaha Performing Artist, conducted a groundbreaking four-way “remote” piano master class, with participating students located in three Chinese cities — each student more than 6,500 miles away.

Students were introduced to a remarkable application of distance learning, thanks to cutting-edge Yamaha “Remote Lesson” technology and four internet-connected Yamaha Disklavier “reproducing” pianos located on ASU’s Tempe campus and at Yamaha piano dealers in Beijing, Nanjing and Wuhan, China. This marks the first-ever connection of Disklavier pianos in four different cities. Virtual piano class Cathal Breslin, assistant professor of piano in ASU’s School of Music, Dance and Theatre and a Yamaha Performing Artist, conducted a groundbreaking four-way “remote” piano master class with participating students located in three Chinese cities — each student more than 6,500 miles away. Photo courtesy ASU Download Full Image

The Yamaha Disklavier, a unique, technologically advanced reproducing piano, enables highly-nuanced performance data – i.e., the actual key strokes and subtle pedal movements made by a performing artist – to be transmitted back and forth between similarly equipped instruments over the internet, with perfectly synchronized video streaming between the locations.

The technology allowed Breslin to teach and evaluate “live” performances by three of his students: Wenyan Han, a first-year doctoral student at ASU, located in Beijing; Ziyi Lyu, a sophomore at ASU, located in Nanjing; and Ruiya Zhong, a freshman at ASU, located in Wuhan — each restricted from returning to ASU’s campus in the United States due to the COVID-19 pandemic.

From his teaching studio at the ASU School of Music, Dance and Theatre in the Herberger Institute for Design and the Arts, Breslin could see, in real-time, the depth of keys and pedals the students used, not on their piano, but the Disklavier in front of him. After the performances, Breslin offered valuable insight to each of the students over video chat while playing his Disklavier remotely to visually illustrate his points. With perfectly synchronized video streaming between the four locations, teacher and student performed back and forth for one another, as if they were sitting on the same piano bench in the same room.  

“The personal nature of piano lessons requires real-time, one-on-one instruction, and this technology allows us to virtually uphold that personal connection,” Breslin said. “Our students are excited by this technology and respond enthusiastically with Disklavier remote lessons. By enhancing the lesson experience, we’re keeping students engaged in an online learning platform.”      

For ASU, one of the top 10 universities in the U.S. for hosting international students, the goal is to bring this opportunity to more global learners.  

Disklavier technology showcases an elevated way in which students can be taught from one piano to another, regardless of where they are located — especially at a time when distance learning is essential for music students around the world. In addition to current established partnerships with Yamaha China and Yamaha Korea, new relationships with Yamaha U.K. and Ireland allow Breslin an even greater global reach.

While video streaming services such as Zoom have become immensely popular in distance learning settings, these technologies are, by their very nature, one-dimensional. In stark contrast, Disklavier Remote Lesson technology seamlessly extends the on-screen piano performance out to the piano itself at all participating locations, bringing a mesmerizing, 3D quality to the learning experience. Moreover, this technology enables prospective students located anywhere in the world to audition remotely without having to travel, providing them an enhanced appreciation for ASU’s forward-thinking music education offerings.

The four-way remote master class followed another, held on Oct. 15 between ASU and Yamaha Seoul in Korea, marking the university’s first remote lesson performed with a foreign country. Three prospective students located in Seoul and applying to ASU participated in the master class taught by Breslin. The “remote” piano master class furthers ASU’s ability to recruit while providing those students interested in applying an opportunity to participate in master classes, giving them exposure to the school, the program and Breslin himself.

The Disklavier technology has inspired Breslin to expand the use of its capabilities. In the future, he hopes to develop a degree program that utilizes Disklavier pianos located in different countries, ultimately offering students the ability to study with him and ASU remotely, without the need for travel.