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

New Microbe Has Potential to Help Rebalance Earth's Nitrogen Cycle

Date: August 23, 2017
Source: University of Alberta
Summary: Microbiologists have now provided unparalleled insight into the Earth's nitrogen cycle, identifying and characterizing the ammonia-oxidizing microbe, Nitrospira inopinata.

New research from University of Alberta and University of Vienna microbiologists provides unparalleled insight into the Earth's nitrogen cycle, identifying and characterizing the ammonia-oxidizing microbe, Nitrospira inopinata. The findings, explained Lisa Stein, co-author and professor of biology, have significant implications for climate change research.

"I consider nitrogen the camouflaged beast in our midst," said Stein.

"Humans are now responsible for adding more fixed nitrogen, in the form of ammonium, to the environment than all natural sources combined. Because of that, the nitrogen cycle has been identified as the most unbalanced biogeochemical cycle on the planet."

The Camouflaged Beast

Earth's nitrogen cycle has been thrown significantly off balance by the process we use to make fertilizer, known as the Haber-Bosch process, which adds massive quantities of fixed nitrogen, or ammonium, to the environment. Downstream effects of excess ammonium has huge environmental implications, from dead zones in our oceans to a greenhouse gas effect 300 times that of carbon dioxide on a molecule to molecule basis.

Isolation and characterization of the Nitrospira inopinata microbe, Stein said, could hold the answers for Earth's nitrogen problem.

Practical Applications

"The Nitrospira inopinata microbe is an ammonium sponge, outcompeting nearly all other bacteria and archaea in its oxidation of ammonium in the environment," explained Stein. "Now that we know how efficient this microbe is, we can explore many practical applications to reduce the amount of ammonium that contributes to environmental problems in our atmosphere, water, and soil."

The applications range from wastewater treatment, with the development of more efficient biofilms, to drinking water and soil purification to climate change research.

"An efficient complete ammonia oxidizer, such as Nitrospira inopinata, may produce less nitrous oxide," explained Kits. "By encouraging our microbe to outgrow other, incomplete oxidizers, we may, in turn, reduce their contribution to the greenhouse gas effect. Further investigation is required."

Story Source:
University of Alberta. "New microbe has potential to help rebalance Earth's nitrogen cycle." ScienceDaily. ScienceDaily, 23 August 2017. www.sciencedaily.com/releases/2017/08/170823142427.htm

Algae: The Final Frontier

Date: June 21, 2017
Source: Carnegie Institution for Science
Summary: Algae dominate the oceans that cover nearly three-quarters of our planet, and produce half of the oxygen that we breathe. And yet fewer than 10 percent of the algae have been formally described in the scientific literature, as noted in a new review.

Algae dominate the oceans that cover nearly three-quarters of our planet, and produce half of the oxygen that we breathe. And yet fewer than 10 percent of the algae have been formally described in the scientific literature, as noted in a new review co-authored by Carnegie's Arthur Grossman in Trends in Plant Science.

Algae are everywhere. They are part of crusts on desert surfaces and form massive blooms in lakes and oceans. They range in size from tiny single-celled organisms to giant kelp.

Algae also play crucial roles in human life. People have eaten "seaweed" (large macroalgae) for millennia. But algae can also represent a health hazard when toxic blooms suffocate lakes and coastlines.

Despite the pervasiveness of algae and their importance in our planet's ecology and in human health and nutrition, there is so much that scientists don't know about them. This lack of knowledge is mostly due to limited support and the need to develop methodologies for probing the various algal groups at the molecular level.

The term 'algae' is used informally to embrace a large variety of photosynthetic organisms that belong to a number of different taxa. To effectively reveal the mysteries of each of these organisms would require creating research processes that are effective for each of them (what works with one often doesn't work with another).

However, some of the latest molecular techniques have allowed scientists to elucidate major genetic processes that have shaped algal evolution. And this improved knowledge has implications beyond basic scientific discovery.

For example, in the future, algae may be used to produce biofuels or to synthesize high-value therapeutic compounds or plastics. Furthermore, with an improved understanding of metabolism in the various algal groups, scientists can better develop strategies to exploit algae for the production of materials -- using them as "cellular factories," in a sense.

Many studies have shown that algae can also adapt to changing environmental conditions. But what are the limits of this ability? And how will the effect of climate change on the world's oceans impact algae and the oxygen that we derive from them?

"In the process of reviewing the state of algal research, we feel that we are on the cusp of a revolution in understanding this group of organisms, their importance in shaping ecosystems worldwide, and the ways in which they can be used to enrich humankind," said Grossman.

Story Source: Carnegie Institution for Science. "Algae: The final frontier." ScienceDaily. ScienceDaily, 21 June 2017. www.sciencedaily.com/releases/2017/06/170621165931.htm