Maize and bacteria: A one-two punch knocks copper out of stamp stand

Megan Zhou

No author given, but is based on materials provided by Michigan Technological University.
Published: March 5, 2014

http://www.sciencedaily.com/releases/2014/03/140305191717.htm

Summary:
Scientists have known for years that bacteria can help remediate contaminated sites, but now Ramakrishna Wusirika, of Michigan Technological University, has discovered that the way you add the bacteria to the plant mix can make a difference. He explains some of the biochemical pathways that allow plants and bacteria to increase the fertility of some of the worst soils, thereby cleaning them. Wusirika focused on the sands of Michigan's Upper Peninsula, which are human-made deserts caused from the remnants of crushed copper ore. Wusirika and his team planted maize in this highly concentrated chemical sand, incorporating bacteria by: mixing it in the stamp seed before planting seed; coating seed with bacteria and planting it; germinating seeds and planting them in soil to which bacteria were added; immersing the roots of maize seedlings in bacteria and planting them in stamp sand, which is the conventional method. After 45 days, as expected, the maize grown with bacteria was significantly larger, from two to five times, and the biggest were those planted as seedlings or as germinated seeds. They also have discovered that the smaller plants pulled more copper out of the stamp sands than the bigger ones. This opens the door to a simple, practical remediation of copper-contaminated soils. Based on the team's research, they believe that the bacteria are improving enzyme activity and increasing soil fertility, partially by freeing phosphorous. The bacteria helps change the copper into a form the plants can take up, enhances photosynthesis and helps the plant make growth hormones.The team believes that this work has applications in remediation, but also in organic agriculture.

Connection:
This article connects to our class' study about the human uses of prokaryotes. Bioremediation, the main focus of this article, is the human's use of other organisms to remove pollutants from water, air, and soil. We learned that cleaning toxic sites was traditionally very expensive, but the use of prokaryotes cuts the cost. This relates to the article because their study shows a simple way of cleaning the copper-contaminated soils. Other bacteria use are attempting to reduce toxins from mine runoff, but is limited due to the bacteria's metabolic processes, such as Thiobacillus adding sulfuric acid to water. From this group's study, the simplicity may not have such a limiting factor, as of now. Also, the team believes that the bacteria has helped the plant by freeing phosphorus that had been locked in the rock. From our studies of plants, we have learned that phosphorus is an essential plant mineral nutrient. It helps nucleic acid and ATP synthesis. Phosphorus is one of the top three nutrients needed, and is often found in fertilizer.