Micro! Polo!: Discovering the beneficial bacteria needed to clean our messes

Micro polo

Bacteria do not have taste buds or eyes. However, they have very fine-tuned senses that relay information about the status inside as well as in their environment. To compete and survive in virtually all environments on the planet, bacteria have evolved to sense and utilize many chemical compounds (most of which are still unknown) for energy and existence no matter how we as humans feel about these compounds. Even toxic compounds are easily metabolized by some bacteria. Whether it is hydrocarbons like petroleum or groundwater contaminated with dry cleaning chemicals, bacteria have evolved pathways to utilize these compounds.

Imagine restoring highly contaminated land for public use without expensive machinery or excessive human exposure. Current research within DOE is working towards this goal through bioremediation, utilizing bacteria with ability to render radioactive or otherwise hazardous material harmless. Even though most microbes presently performing this task are unknown, meta-sequencing projects are turning up a common set of genes (and proteins) necessary for this process.

Let’s briefly take a look at some of these toxic compounds.

TCE to DCE

Here we have (from left to right) perchloroethene, trichloroethene, and dichloroethene. PCE is a common chemical used in dry cleaning and easily contaminates groundwater. It’s removal is expensive and time-consuming, not to mention dangerous given its toxicity. However, a small number (so far) of bacteria can actually use these chemicals during metabolism when oxygen is absent from the environment (deep underground, for example). DCE is still considered a contaminant, so, how do we get rid of it? A group of bacteria discovered not long ago actually have the complete set of genes to breakdown perchloroethene to ethylene, Dehalococcoides. These bacteria have small genomes relative to the average bacterium but contain a set of genes that will render these contaminants essentially harmless.

vinyl chloride and ethylene

Vinyl chloride, the next step in PCE degradation can be further reduced to ethylene by an enzyme called vinyl chloride reductase (Vcr). To date, only Dehalococcoides are found to contain Vcr genes.

Next, I will talk about other common contaminants and the wonderful bacteria that can clean them up.

“Write what you know about” – Mark Twain

Good advice from a great communicator. From now on, the majority of posts will relate in some way to bacteria, especially microbial genomics. Most of the remainder of posts will be related to science communication and education.

Why bother spreading the love for the little creatures? I believe this quote from microbialgenomics.energy.gov sums it up:

By some estimates, microbes make up about 60% of the earth’s biomass, yet less than 1% of microbial species have been identified. Because most do not cause disease in humans, animals, or plants and are difficult to culture, they have received little attention. Identifying and harnessing their unique capabilities will offer us new solutions to longstanding challenges in environmental and waste cleanup, energy production and use, medicine, industrial processes, agriculture, and other areas. Scientists also are starting to appreciate the role played by microbes in global climate processes, and we can expect insights about both the biological underpinnings of climate change and the contributions of microbes to earth’s biosphere. Their capabilities soon will be added to the list of traditional commercial uses for microbes in the brewing, baking, dairy, and other industries.

There is so much we don’t know about microbes. However, we are beginning to understand their enormous¬†adaptability. Whether it is 30,000 feet above the ground or two miles beneath it, bacteria can inevitably survive. I will now focus on getting the word out about the little guys who can’t speak for themselves.

Microbes can be used in soil cleanup
Microbes can be used in soil cleanup (Photo credit: Wikipedia)