Newly Discovered Bacterium Rids Problematic Pair of Toxic Groundwater Contaminants

Date: October 9, 2018
Source: New Jersey Institute of Technology
Summary: Researchers have detailed the discovery of the first bacterium known capable of simultaneously degrading the pair of chemical contaminants -- 1,4-Dioxane and 1,1-DCE.

Image of DD4 cells.
Credit: NJIT, Mengyan Li

Known as a chemical manufacturing by-product of many cosmetics and home cleaning products, the industrial solvent 1,4-Dioxane is now considered by the Environmental Protection Agency to be an "emerging contaminant" and "likely human carcinogen" that can be found at thousands of groundwater sites nationally -- potentially representing a multi-billion dollar environmental remediation challenge.

However, it is the contaminant's frequent co-existence with another toxic chemical -- 1,1-Dichloroethylene (1,1-DCE) -- that has been found to aid in 1,4-dioxane's resistance to certain remediation strategies, including degradation by naturally-occurring microbes.

Now, New Jersey Institute of Technology (NJIT) researchers have detailed the discovery of the first bacterium known capable of simultaneously degrading the pair of chemical contaminants -- 1,4-Dioxane and 1,1-DCE. The study, published in Environmental Science & Technology Letters, also showcases the efficiency of the microbe, called Azoarcus sp. DD4 (DD4), in reducing 1,4-dioxane and 1,1-DCE levels in co-contaminated groundwater samples.

"Nationwide, researchers have found that more than 80% of the groundwater sites contaminated with 1,4-dioxane also contain 1,1-DCE," said Mengyan Li, assistant professor of chemistry and environmental science at NJIT. "This pair of chemicals are toxic and costly to remove from the environment because the pair have very different properties that typically require separate treatment solutions. Biodegradation by DD4 is the first biological method we have found for treating both compounds concurrently, and it is also environmentally-friendly and cost-efficient."

Li's research team initially discovered the DD4 microbe from activated sludge samples collected from a municipal wastewater treatment facility. In the lab, Li's team was able to isolate and analyze DD4's ability to degrade 1,4-dioxane and 1,1-DCE simultaneously in contaminated groundwater samples over a two-week period.

Applying the microbe to the field samples, Li's team observed that concentration of 1,4-dioxane was degraded from 10 parts-per-million (10 ppm) -- or 3,000 times the limit of the EPA's guidance level of 0.35 parts-per-billion (0.35 ppb) -- to under 0.38 ppb. The lab also found 1,1-DCE concentration levels reduced from over 3 ppm to below 0.02 ppm.

Notably, DD4 displayed resistance to cellular toxicity produced by the metabolites of 1,1-DCE, which typically inhibit the ability of other bacteria capable of degrading 1,4-dioxane. Li's team observed that although DD4 was partially inhibited in its ability to degrade 1,4-dioxane when excessive amounts of 1,1-DCE were artificially spiked in the water samples, 1,4-dioxane degradation capability immediately recovered once the microbe had depleted 1,1-DCE.

"Overall, we were impressed by the performance of DD4," said Li. "We did not add nutrients like ammonia for the microbe to feed on, or other facilitators that might enhance the bacterium's activity. This demonstrated to us the potential of this bacterium for future use in the field."

In an analysis of the genetic makeup of DD4, Li's lab identified a potentially key gene related to the microbe's chemical degradation activity. Li says that the gene encodes for an enzyme, called soluble di-iron monooxygenase (SDIMO), with versatile capabilities of breaking down chemical pollutants. "We want to characterize it (this enzyme) further to see if we can better learn the mechanism underlying how DD4 degrades these contaminants." said Li.

Along with DD4's 1,1-DCE-resistance and ability to degrade the co-contaminants concurrently, Li says the bacterium possesses several other key traits that make it conducive as a potential bioremediation solution at contaminated groundwater sites -- such as its ability to disperse freely through water to remediate larger areas of contamination, rather than aggregating like other bacterial treatments. The microbe can also be cultured rapidly and can sustain for extended periods with limited nutrient source.

"We tested the bacterium in normal refrigerated temperature over three days and its viability remained above 80%," said Li. "After a week, half were still alive. This makes it even more desirable because it would be able to survive the delivery time from the lab to contaminated sites."

Li's lab is now conducting further tests of the bacterium in the lab to better understand how DD4 might perform at contaminated water sites. With feasibility tests already underway, Li says his team could begin field demonstrations of DD4 as a water treatment solution for 1,4-dioxane and 1,1-DCE contamination sites as early as next year.

"Ideally, we may inject the bacteria into the center of a contamination zone, or try growing them on the surface of bio-barriers that help stop spread of contamination," said Li. "First, we'd like to do more tests and possibly develop a gene marker that helps us assess the bacteria's performance. Then, we would like to move into the field."

Story Source:
New Jersey Institute of Technology. "Newly discovered bacterium rids problematic pair of toxic groundwater contaminants." ScienceDaily. ScienceDaily, 9 October 2018. https://www.sciencedaily.com/releases/2018/10/181009115019.htm

A Biological Solution to Carbon Capture and Recycling?

E. coli bacteria shown to be excellent at CO₂ conversion

Date: January 8, 2018
Source: University of Dundee
Summary: Scientists have discovered that E. coli bacteria could hold the key to an efficient method of capturing and storing or recycling carbon dioxide. They have developed a process that enables the E. coli bacterium to act as a very efficient carbon capture device.

Rendering of bacteria.
Credit: © 7activestudio / Fotolia

Scientists at the University of Dundee have discovered that E. coli bacteria could hold the key to an efficient method of capturing and storing or recycling carbon dioxide.

Cutting carbon dioxide (CO₂) emissions to slow down and even reverse global warming has been posited as humankind's greatest challenge. It is a goal that is subject to considerable political and societal hurdles, but it also remains a technological challenge.

New ways of capturing and storing CO₂ will be needed. Now, normally harmless gut bacteria have been shown to have the ability to play a crucial role.

Professor Frank Sargent and colleagues at the University of Dundee's School of Life Sciences, working with local industry partners Sasol UK and Ingenza Ltd, have developed a process that enables the E. coli bacterium to act as a very efficient carbon capture device.

Professor Sargent said, "Reducing carbon dioxide emissions will require a basket of different solutions and nature offers some exciting options. Microscopic, single-celled bacteria are used to living in extreme environments and often perform chemical reactions that plants and animals cannot do.

"For example, the E. coli bacterium can grow in the complete absence of oxygen. When it does this it makes a special metal-containing enzyme, called 'FHL', which can interconvert gaseous carbon dioxide with liquid formic acid. This could provide an opportunity to capture carbon dioxide into a manageable product that is easily stored, controlled or even used to make other things. The trouble is, the normal conversion process is slow and sometime unreliable.

"What we have done is develop a process that enables the E. coli bacterium to operate as a very efficient biological carbon capture device. When the bacteria containing the FHL enzyme are placed under pressurised carbon dioxide and hydrogen gas mixtures -- up to 10 atmospheres of pressure -- then 100 per cent conversion of the carbon dioxide to formic acid is observed. The reaction happens quickly, over a few hours, and at ambient temperatures.

"This could be an important breakthrough in biotechnology. It should be possible to optimize the system still further and finally develop a 'microbial cell factory' that could be used to mop up carbon dioxide from many different types of industry.

"Not all bacteria are bad. Some might even save the planet."

Not only capturing carbon dioxide but storing or recycling it is a major issue. There are millions of tonnes of CO₂ being pumped into the atmosphere every year. For the UK alone, the net emission of CO₂ in 2015 was 404 million tonnes. There is a significant question of where can we put it all even if we capture it, with current suggestions including pumping it underground in to empty oil and gas fields.

"The E. coli solution we have found isn't only attractive as a carbon capture technology, it converts it into a liquid that is stable and comparatively easily stored," said Professor Sargent.

"Formic acid also has industrial uses, from a preservative and antibacterial agent in livestock feed, a coagulant in the production of rubber, and, in salt form, a de-icer for airport runways. It could also be potentially recycled into biological processes that produce CO₂, forming a virtuous loop."

Story Source:
University of Dundee. "A biological solution to carbon capture and recycling? E. coli bacteria shown to be excellent at CO₂ conversion." ScienceDaily. ScienceDaily, 8 January 2018. https://www.sciencedaily.com/releases/2018/01/180108101359.htm

Bacteria-Coated Nanofiber Electrodes Clean Pollutants in Wastewater

Date: June 28, 2017
Source: Cornell University
Summary: Researchers may have created an innovative, cost-competitive electrode material for cleaning pollutants in wastewater.

Cornell University materials scientists and bioelectrochemical engineers may have created an innovative, cost-competitive electrode material for cleaning pollutants in wastewater.

The researchers created electro-spun carbon nanofiber electrodes and coated them with a conductive polymer, called PEDOT, to compete with carbon cloth electrodes available on the market. When the PEDOT coating is applied, an electrically active layer of bacteria -- Geobacter sulfurreducens -- naturally grows to create electricity and transfer electrons to the novel electrode.

The conducting nanofibers create a favorable surface for this bacteria, which digests pollutants from the wastewater and produces electricity, according to the research.

"Electrodes are expensive to make now, and this material could bring the price of electrodes way down, making it easier to clean up polluted water," said co-lead author Juan Guzman, a doctoral candidate in the field of biological and environmental engineering. Under a microscope, the carbon nanofiber electrode resembles a kitchen scrubber.

The electrode was made by co-lead author Meryem Pehlivaner, currently a doctoral student at Northeastern University, with senior author Margaret Frey, professor of fiber science and an associate dean of the College of Human Ecology. Pehlivaner fabricated the carbon nanofibers via electrospinning and carbonization processes. After a few hours electrospinning, a thick nanofiber sheet -- visible to the naked eye -- emerges.

Pehlivaner reached out to Guzman and senior author Lars Angenent, professor of biological and environmental engineering, for collaboration in applying the carbon nanofiber electrodes to simultaneous wastewater treatment and production of electrical energy.

The customizable carbon nanofiber electrode was used for its high porosity, surface area and biocompatibility with the bacteria. By adhering PEDOT, the material gets an improved function, according to the researchers.

Guzman said wastewater treatment plants do not employ this method -- yet. On a large scale, the bacteria at the electrode could capture and degrade pollutants from the wastewater that flows by it. Such a technology can improve wastewater treatment by allowing systems to take up less land and increase throughput.

Concepts like this happen on campuses where faculty and students want to communicate and collaborate, Angenent said. "This defines radical collaboration," he said. "We have fiber scientists talking to environmental engineers, from two very different Cornell colleges, to create reality from an idea -- that was more or less a hunch -- that will make cleaning wastewater better and a little more inexpensive."

Story Source: Cornell University. "Bacteria-coated nanofiber electrodes clean pollutants in wastewater." ScienceDaily. ScienceDaily, 28 June 2017. www.sciencedaily.com/releases/2017/06/170628144829.htm

Chance Find Has Big Implications for Water Treatment's Costs And Carbon Footprint

Date: March 24, 2017
Source: Engineering and Physical Sciences Research Council
Summary: A type of bacteria accidentally discovered during research could fundamentally reshape efforts to cut the huge amount of electricity consumed during wastewater clean-up. The discovery has upended a century of conventional thinking. The microorganisms -- 'comammox' (complete ammonia oxidizing) bacteria -- can completely turn ammonia into nitrates.

A type of bacteria accidentally discovered during research supported by the Engineering and Physical Sciences Research Council (EPSRC) could fundamentally re-shape efforts to cut the huge amount of electricity consumed during wastewater clean-up.

The discovery has upended a century of conventional thinking. The microorganisms -'comammox' (complete ammonia oxidising) bacteria -- can completely turn ammonia into nitrates. Traditionally, this vital step in removing nitrogen from wastewater has involved using two different microorganisms in a two-step approach: ammonia is oxidised into nitrites that are then oxidised into nitrates, which are turned into nitrogen gas and flared off harmlessly.

The outcome could be a big rethink regarding the energy-saving innovations developed over the last two to three decades in the field of nitrogen removal. Wastewater treatment is a huge consumer of electricity, accounting for 2-3 per cent of all power usage in western countries, and no less than 30 per cent of its energy bill results from the need to remove nitrogen. Most of the sector's efforts to reduce its energy use have focused on the two-microorganism approach.

The discovery was made by scientists working on the EPSRC-funded Healthy Drinking Water project, which is being led by the University of Glasgow and is due to publish its core findings later this year.

Dr Ameet Pinto has led the team, which has worked in collaboration with the University of Michigan in the US. He says: "This discovery took us completely by surprise. It's a superb example of how EPSRC support provides a secure platform for a can-do environment enabling researchers to achieve important spin-off breakthroughs in addition to the primary goals of their research."

Comammox was found in a drinking water system in the US. Other research groups have also detected it in wastewater treatment plants, in groundwater and even in aquaculture systems.

Dr Pinto says: "The discovery of a single microorganism capable of full nitrification will have a significant impact on our understanding of the nitrogen cycle and on efforts to manage nitrogen pollution. The potential is there for the wastewater treatment sector to exploit this breakthrough, which other teams in Europe have made in parallel with us.

"That would be an important step towards informing the development of robust approaches in terms of cutting costs and reducing carbon emissions associated with generating the huge amounts of electricity that the sector uses. It's a great story to highlight on World Water Day."

Story Source: Engineering and Physical Sciences Research Council. "Chance find has big implications for water treatment's costs and carbon footprint." ScienceDaily. ScienceDaily, 24 March 2017. www.sciencedaily.com/releases/2017/03/170324104906.htm

Antibiotic Resistance: It's a Social Thing

Date: March 15, 2016
Source: University of York
Summary: Trace concentrations of antibiotic, such as those found in sewage outfalls, are enough to enable bacteria to keep antibiotic resistance, new research has found. The concentrations are much lower than previously anticipated, and help to explain why antibiotic resistance is so persistent in the environment.

Aerial view of sewage water treatment plant.
Credit: © josefkubes / Fotolia

Trace concentrations of antibiotic, such as those found in sewage outfalls, are enough to enable bacteria to keep antibiotic resistance, new research from the University of York has found. The concentrations are much lower than previously anticipated, and help to explain why antibiotic resistance is so persistent in the environment.

Antibiotic resistance can work in different ways. The research described the different mechanisms of resistance as either selfish or co-operative. A selfish drug resistance only benefits the individual cell with the resistance while a co-operative antibiotic resistance benefits both the resistant cell and surrounding cells whether they are resistant or not.

The researchers analysed a plasmid called RK2 in Escherichia coli, a bacterium which can cause infectious diarrhea. RK2 encodes both co-operative resistance to the antibiotic ampicillin and selfish resistance to another antibiotic, tetracycline. They found that selfish drug resistance is selected for at concentrations of antibiotic around 100-fold lower than would be expected -- equivalent to the residues of antibiotics found in contaminated sewage outfalls.

The study, which is published in Antimicrobial Agents and Chemotherapy (AAC), involved Professor Michael Brockhurst, Dr Jamie Wood and PhD student Michael Bottery in the Departments of Biology and Mathematics at York. The work was supported by the European Research Council under the EU's Seventh Framework Programme and the Wellcome Trust.

Dr Wood said: "The most common way bacteria become resistant to antibiotics is through horizontal gene transfer. Small bits of DNA, called plasmids, contain the resistance and can hop from one bacteria to another. Worse still, plasmids often contain more than one resistance."

Michael Bottery added: "There is a reservoir of antibiotic resistance out there which bacteria can pick and choose from. What we have found is some of that resistance can exist at much lower concentrations of antibiotic than previously understood."

Source: University of York. "Antibiotic resistance: it's a social thing." ScienceDaily. ScienceDaily, 15 March 2016. .

Our Water Pipes Crawl with Millions of Bacteria

Date: December 16, 2015

Source: Lund University

Summary: Our drinking water is to a large extent purified by millions of "good bacteria" found in water pipes and purification plants, Swedish researchers have found. So far, the knowledge about them has been practically non-existent, but this new research is about to change that.

A glass of water contains millions of bacteria, say researchers.
Credit: © Andrey Kuzmin / Fotolia

Researchers from Lund University in Sweden have discovered that our drinking water is to a large extent purified by millions of "good bacteria" found in water pipes and purification plants. So far, the knowledge about them has been practically non-existent, but this new research is about to change that.

A glass of clean drinking water actually contains ten million bacteria! But that is as it should be -- clean tap water always contains harmless bacteria. These bacteria and other microbes grow in the drinking water treatment plant and on the inside of our water pipes, which can be seen in the form of a thin, sticky coating -- a so-called biofilm. All surfaces from the raw water intake to the tap are covered in this biofilm.

Findings by researchers in Applied Microbiology and Water Resources Engineering show that the diversity of species of bacteria in water pipes is huge, and that bacteria may play a larger role than previously thought. Among other things, the researchers suspect that a large part of water purification takes place in the pipes and not only in water purification plants.

"A previously completely unknown ecosystem has revealed itself to us. Formerly, you could hardly see any bacteria at all and now, thanks to techniques such as massive DNA sequencing and flow cytometry, we suddenly see eighty thousand bacteria per millilitre in drinking water," says researcher Catherine Paul enthusiastically.

"From having been in the dark with a flashlight, we are now in a brightly lit room, but it is only one room. How many different rooms are in the house is also an interesting question!" she continues.

The work of doctoral student Katharina Lührig, who works together with Catherine, professors Peter Rådström and Kenneth Persson, and colleagues Björn Canbäck and Tomas Johansson has been published in Microbes and Environments.

The results have led to lively discussions within the industry about the role of biofilms in drinking water.

At least a couple of thousand different species live in the water pipes. According to the researchers there is a connection between the composition of bacteria and water quality.

"We suspect there are 'good' bacteria that help purify the water and keep it safe -- similar to what happens in our bodies. Our intestines are full of bacteria, and most the time when we are healthy, they help us digest our food and fight illness, says Catherine Paul.

Although the research was conducted in southern Sweden, bacteria and biofilms are found all over the world, in plumbing, taps and water pipes. This knowledge will be very useful for countries when updating and improving their water pipe systems.

"The hope is that we eventually may be able to control the composition and quality of water in the water supply to steer the growth of 'good' bacteria that can help purify the water even more efficiently than today," says Catherine Paul.


Story Source:
The above post is reprinted from materials provided by Lund University.

Chlorine Use in Sewage Treatment Could Promote Antibiotic Resistance

Date: March 22, 2015

Source: American Chemical Society

Graduate student Nicole Kennedy measures the antibiotic activity of various samples in the lab.
Credit: Olya Keen

Chlorine, a disinfectant commonly used in most wastewater treatment plants, may be failing to completely eliminate pharmaceuticals from wastes. As a result, trace levels of these substances get discharged from the plants to the nation's waterways. And now, scientists are reporting preliminary studies that show chlorine treatment may encourage the formation of new, unknown antibiotics that could also enter the environment, potentially contributing to the growing problem of antibiotic resistance.

The research, which will be presented today at the 249th National Meeting & Exposition of the American Chemical Society (ACS), suggests that a re-evaluation of wastewater treatment and disinfection practices is needed.

"Pharmaceuticals that get out into the environment can harm aquatic life, making them react slowly in the wild and disrupting their hormone systems," notes Olya Keen, Ph.D. She adds that increased antibiotic exposure, even at low levels in the environment, can lead to development of antibiotic-resistant microbes and a general weakening of antibiotics' abilities to fight bacterial infections in humans.

"Treated wastewater is one of the major sources of pharmaceuticals and antibiotics in the environment," says Keen. "Wastewater treatment facilities were not designed to remove these drugs. The molecules are typically very stable and do not easily get biodegraded. Instead, most just pass through the treatment facility and into the aquatic environment."

But besides failing to remove all drugs from wastewater, sewage treatment facilities using chlorine may have the unintended consequences of encouraging the formation of other antibiotics in the discharged water. Keen, graduate student Nicole Kennedy and others in her team at the University of North Carolina at Charlotte ran several lab experiments and found that exposing doxycycline, a common antibiotic, to chlorine in wastewater increased the antibiotic properties of their samples.

"Surprisingly, we found that the products formed in the lab sample were even stronger antibiotics than doxycycline, the parent and starting compound," she adds. Keen has not yet identified all the properties of these "transformation products," and that research is now underway. She notes that these compounds could turn out to be previously unidentified antibiotics.

Keen explains that the best solution may be to decrease the amount of these drugs that reach a treatment plant in the first place. Currently, disposal of pharmaceuticals is not regulated, however. So she urges a greater emphasis on collecting and incinerating old pharmaceuticals, rather than dumping them down the drain or placing them in the trash, which can lead to harmful environmental exposures.

In addition, this research has applications to drinking water treatment systems, most of which also use chlorine as a disinfectant, she says. To purify drinking water, chlorine must remain in the distribution piping system for hours, which blocks microbes from growing. But this also provides ample time for chlorine to interact with pharmaceuticals that may be in the water, encouraging development of new antibiotic compounds.

Story Source: "Chlorine use in sewage treatment could promote antibiotic resistance." ScienceDaily. ScienceDaily, 22 March 2015. www.sciencedaily.com/releases/2015/03/150322080204.htm

Gut Bacteria from a Worm Can Degrade Plastic

Date: December 3, 2014

Source: American Chemical Society

Summary: Plastic is well-known for sticking around in the environment for years without breaking down, contributing significantly to litter and landfills. But scientists have now discovered that bacteria from the guts of a worm known to munch on food packaging can degrade polyethylene, the most common plastic.The finding could lead to new ways to help get rid of the otherwise persistent waste, the scientists say.

Some bacteria from the guts of waxworms could help us eliminate plastic trash.
Credit: ACS

Plastic is well-known for sticking around in the environment for years without breaking down, contributing significantly to litter and landfills. But scientists have now discovered that bacteria from the guts of a worm known to munch on food packaging can degrade polyethylene, the most common plastic. Reported in the ACS journal Environmental Science & Technology, the finding could lead to new ways to help get rid of the otherwise persistent waste, the scientists say.

Jun Yang and colleagues point out that the global plastics industry churns out about 140 million tons of polyethylene every year. Much of it goes into the bags, bottles and boxes that many of us use regularly -- and then throw out. Scientists have been trying to figure out for years how to make this plastic trash go away. Some of the most recent studies have tried siccing bacteria on plastic to degrade it, but these required first exposing the plastic to light or heat. Yang's team wanted to find bacteria that could degrade polyethylene in one step.

The researchers turned to a plastic-eating moth larva, known as a waxworm. They found that at least two strains of the waxworm's gut microbes could degrade polyethylene without a pretreatment step. They say the results point toward a new, more direct way to biodegrade plastic.

The authors acknowledge funding from the National Natural Science Foundation of China, the National Basic Research Program of China and the Shenzhen Key Laboratory of Bioenergy.

Story Source: The above story is based on materials provided by American Chemical Society.