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Global warming and forest soil micro biomes

Thursday, July 19, 2012, by Sonia Filipczak
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Global Warming has become a topic under much debate, yet carrying implications that affect everyone. Whether you are young or old, plant, animal, or microbe, some of the obvious signs such as less snow in the winter and unbearably hot summers should remind us how much of an impact each individual has on our world. Among all of the individuals on this planet, soil microbes make up a large population and their response to climate change should be of concern. After all, there are more microbes in a teaspoon of soil than people on Earth!

Similar to us, microbial communities are affected by the rise or fall in temperature, causing them to become more or less active. Why is this important, you may ask? Well, microbes are instrumental in the cycling of CO2 as well as breaking down and recycling nutrients from decomposing material to produce fresh nutrients needed for many things that sprout from the soil. This summer I am researching with Dr. Jeff Blanchard, of UMass Amherst, to analyze and identify what species of microbes are present in the soil and theorize how they will be affected as Earth’s temperature increases. 

Part of my experiment is looking into the microbes that are present in the soil and how that influences the amount of CO2 that is being respired as a result of the temperature flux. The results come from two Harvard Forest plots, one on Prospect Hill the other in Barre Woods. At each site there are two plots, one that serves as a control, the other is warmed year round, 5 degrees Celsius above ambient temperature. Since the Prospect Hill warming plot has been under observation for the past 20 years, the longest of this sort, we have been able to identify trends that other researchers were not able to see. For example, over a short period of time, CO2 respiration has been documented to rise and then fall. However, given the extra 5-10 years in this experiment over others, we have observed that the CO2 respiration has again risen. An important point to note is that warming increases respiration thereby accelerating climate change. In our experiment, warming has decreased the organic layer, with broken down leaves, to half the level of the control. Ultimately, through warming, we are essentially turning soil into atmospheric gases. Now that we have observed this change, we must identify which microbes are present and responsible for what is going on under our feet! 

To identify the microbes, we extract DNA from soil samples through a lot of really cool steps, including placing less than 0.5g of soil into “bead beating” tubes, which are filled with little beads that agitate and crack open cells; this step is followed by mixing the soil with various solutions and giving it a good shake. To do so, the tubes are taped down on a gyrating machine top also known as a “vortex”. After this, the tubes are then centrifuged for a few minutes, as well as going through a series of extractions to remove the supernatant to get a pure sample; it is now ready for PCR, or polymerase chain reaction. This is a biochemical technology, in molecular biology, that amplifies a single or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence. Once this is completed, the information is sent out to be sequenced at a lab.

The other part of my project is Bioinformatics. Strange word? Well you can think of it as the bridge between the computer and science world. With the information we will receive from the lab, I will write a computer program to scan through the sequences and match all similar traits that will help me, identify microbial species. 

Doing this will help bring us one step closer to the answer of a question that we must consider: how will a warmer climate affect the microbes and ultimately us?