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

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.

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, 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.

Related articles

• Cleaning up the Land – vinyl chloride (promontoryscience.wordpress.com)
• MyTH: A new weekly series about one bacterial species. First Post: Escherichia coli ” Taking Science to the People (mhrussel.wordpress.com)
• Oil-eating bacteria clearing up oil spill (ibmonthlyswe.wordpress.com)
• MyTH: A new weekly series about one bacterial species. First Post: Escherichia coli (mhrussel.wordpress.com)

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