Biological cleanup discovered for certain 'forever chemicals'
Two species of naturally-occurring bacteria found to breakdown
chlorinated 'forever chemicals,' AKA PFAS

Date:
May 31, 2023
Source:
University of California - Riverside
Summary:
Chemical and environmental engineering scientists have identified
two species of bacteria found in soil that break down a class of
stubborn 'forever chemicals'-- per- and poly-fluoroalkyl substances,
or PFAS, that have contaminated groundwater below industrial and
military sites throughout the nation. The discovery gives hope
for low-cost biological cleanup of these pollutants.


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FULL STORY ========================================================================== University of California, Riverside, chemical and environmental
engineering scientists have identified two species of bacteria found
in soil that break down a class of stubborn "forever chemicals," giving
hope for low-cost biological cleanup of industrial pollutants.

These bacteria destroy a subgroup of per- and poly-fluoroalkyl substances,
or PFAS, that have one or more chlorine atoms within their chemical
structure, Yujie Men, an assistant professor in the Bourns College of Engineering, and her UCR colleagues, reported in the journal Natural
Water.

Unhealthful forever chemicals persist in the environment for decades
or much longer because of their unusually strong carbon-to-fluorine
bonds. Remarkably, the UCR team found that the bacteria cleave the
pollutant's chlorine-carbon bonds, which starts a chain of reactions
that destroy the forever chemical structures, rendering them harmless.

"What we discovered is that bacteria can do carbon-chlorine bond cleavage first, generating unstable intermediates," Men said. "And then those
unstable intermediates undergo spontaneous defluorination, which is the cleavage of the carbon-fluorine bond." Chlorinated PFAS are a large
group in the forever chemical family of thousands of compounds. They
include a variety of non-flammable hydraulic fluids used in industry and compounds used to make chemically stable films that serve as moisture
barriers in various industrial, packaging, and electronic applications.

The two bacteria species -- Desulfovibrio aminophilus and Sporomusa sphaeroides-- identified by Men's group are naturally occurring and are
known to live in the subterranean microbiomes where groundwater may be contaminated with PFAS. For expedited cleanups, an inexpensive nutrient,
such as methanol, could be injected into groundwater to promote bacterial growth. This would greatly increase the bacteria's presence to destroy
the pollutants more effectively, Men said. If the bacteria are not
already present, the contaminated water could be inoculated with one of
the bacterium species.

The title of the paper is "Substantial defluorination of polychlorofluorocarboxylic acids triggered by anaerobic microbial
hydrolytic dichlorination." Men is the corresponding author and Bosen
Jin, a UCR chemical and environmental engineering graduate student,
is the lead author. Other UCR co-authors are postdoc Jinyu Gao; former
postdoc Huaqing Liu; former graduate students Shun Che and Yaochun Yu;
and Associate Professor Jinyong Liu.

The study expands on earlier work by Men, in which she demonstrated
that microbes can breakdown a stubborn class of PFAS called fluorinated carboxylic acids.

Microbes have long been used for biological cleanup of oil spills
and other industrial pollutants, including the industrial solvent trichloroethylene or TCE, which Men has studied.

But what's known about using microorganisms to clean up PFAS is still
in its infancy, Men said. Her discovery shows great promise because
biological treatments, if effective pollutant-eating microbes are
available, are generally less costly and more environmentally friendly
than chemical treatments.

Pollutant-eating microbes can also be injected into difficult-to-reach locations underground.

Men's latest PFAS study comes as the U.S. Environmental Protection Agency
is promulgating new regulations to spur cleanups of PFAS-contaminated groundwater sites throughout the nation because these chemicals have been linked to a host of ill health effects, including cancer, kidney disease,
and hormone disruptions.

* RELATED_TOPICS
o Plants_&_Animals
# Bacteria # New_Species # Microbes_and_More # Soil_Types
o Earth_&_Climate
# Pollution # Geochemistry # Air_Quality # Air_Pollution
* RELATED_TERMS
o Soil_contamination o Environmental_engineering o Pesticide
o Pollution o Civil_engineering o Endospore o PCB o Soil_science

========================================================================== Story Source: Materials provided by
University_of_California_-_Riverside. Original written by David
Danelski. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Bosen Jin, Huaqing Liu, Shun Che, Jinyu Gao, Yaochun Yu, Jinyong
Liu,
Yujie Men. Substantial defluorination of polychlorofluorocarboxylic
acids triggered by anaerobic microbial hydrolytic
dechlorination. Nature Water, 2023; 1 (5): 451 DOI:
10.1038/s44221-023-00077-6 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/05/230531102022.htm

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