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Some aggressive fungi, alfalfa, lotus plants, and phytoremediation

February 5, 2012

Holotype of Medicago sativa L. f. salaverryensis J. F. Macbr. collected by J. F. Macbride & Featherstone in 1922 in Peru.

Today’s post is a bit of a vocabulary lesson, at least for the non-scientific among us. I will kick things off with a definition or two:
  • Biodegradation – “Transformation of a substance into new compounds through biochemical reactions or the actions of microorganisms such as bacteria.” – U.S. Geological Survey, 2007

From that definition, I stumbled across this one:

  • Phytoremediation–”the use of plants to clean up polluted soil and water resources”

For the botanists among us (not me), this concept will be nothing new, but it is capturing my fascination for the time being. The process of transforming substances through biological agents, organically, has some significant potential for environmental purposes as the article discussing the breakdown of plastics through fungi makes abundantly clear. Generally, this is done through bacterial agents in the fungi (or other biological entity) and plastic is generally not the food of choice. At least until the introduction of Pestalotiopsis microspora, which not only breaks down plastic (in landfills), but survives on it. The article in question is below:

  • Jonathan R. Russell, Jeffrey Huang, Pria Anand, Kaury Kucera, Amanda G. Sandoval, Kathleen W. Dantzler, DaShawn Hickman, Justin Jee, Farrah M. Kimovec, David Koppstein, Daniel H. Marks, Paul A. Mittermiller, Salvador Joel Núñez, Marina Santiago, Maria A. Townes, Michael Vishnevetsky, Neely E. Williams, Mario Percy Núñez Vargas, Lori-Ann Boulanger, Carol Bascom-Slack and Scott A. Strobel (2011). Biodegradation of Polyester Polyurethane by Endophytic Fungi. Applied Environmental Microbiology, September 2011, 77(17).

What is remarkable is that the fungi, Pestalotiopsis microspora, is basically the first plant that anyone has found to survive on plastic alone (well, the polyurethane in the plastic) and it does so in an almost completely oxygen-free environment. Which are the kind of conditions one finds at the bottom of a landfill. Remarkable. Fungus that breaks down the plastic in landfills; that seems like quite an extraordinary evolutionary leap perhaps fueled by necessity.

This article had me looking around for other instances of biological agents breaking down hazardous elements in the  environments and apparently this is quite a trend. Please forgive me those who know all about this; I just find it remarkable what plants (and fungi!) are capable of in the most inhospitable of circumstances. Life just finds a way.

Another instance is the following:

  • Wang, L.; Samac, D.; Shapir, N.; Wackett, L.; Vance, C.; Olszewski, N.; and Sadowsky, M. (2005). Biodegradation of atrazine in transgenic plants expressing a modified bacterial atrazine chlorohydrolase (atzA) gene. Plant Biotechnology Journal (2005) 3, pp. 475–486.

While 99.9% of that article is beyond my meager understanding, the gist of it is that hydroponically grown alfalfa (and tobacco plants) might be able to be used to dechlorinate soil and soil water with atrazine, a controversial fairly common herbicide that has been known to cause birth defects and menstrual problems when consumed (at levels even below government-approved standards). So, turn the alfalfa and tobacco loose and let it swallow all that atrazine. I am curious to do some more research on this to see if it did indeed pan out that way as the article was written in 2005. Alfalfa is a particularly useful (and especially active) plant as made evident in this Use record from West Africa.

Another article goes as far to suggest (and once again, I would like to learn more about the success of these efforts) that plants can be genetically modified to be more thorough and efficient toxin consumers.

The article introduces the third vocabulary word that I learned today, xenobiotics. Xenobiotics are chemicals found in an organism that are generally not supposed to be there, such as pollutants. In the above article, the authors suggest that plants are used to detoxify xenobiotics and can be bred to do so more efficiently. There are numerous examples of other experiments with phytoremediation, but one of my favorites is the Lotus Project at Auburn University. This project is attempting to use lotus leaves for phytoremediation purposes. The video below explains it better than I can.

I expect I will write more on this subject in the coming months as it particularly fascinating. If you want me to highlight some particular examples or experiments, please feel free to send them my way. 


2 Comments leave one →
  1. ladybuglover permalink
    May 4, 2012 4:46 pm

    I recently did a science project on this same topic! I used alfalfa (one of the plants mentioned) to decontaminate soil that had oil in it. In my project, I found that the alfalfa was great at this, and removed all the oil (as far as I can tell) in only 2 weeks! This is a very interesting concept, and I would like to learn more about it.

    • May 4, 2012 6:46 pm

      Interesting project there. I am curious to see more information on this process myself as it does look promising. Did you happen to take any pictures of your project? I will do some more research to see if I can learn more and perhaps do another post. Thanks for reading!

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