Friday, October 16, 2009
Evidence vs Theory
The posts on systems got me thinking: evidence or logic, which should we trust more? Part of the project I'm involved in looks at how lignin degrades compared to cellulose. Lignin is a carbon molecule with many different bonds making it very hard to degrade. It requires many different kinds of enzymes working in concert. Because of this, only a hand full of microorganisms can degrade it. Cellulose on the other hand is a carbon molecule with simple linkages that takes just a few enzymes to degrade. Many microorganisms can degrade cellulose because of this. So by logic, cellulose should degrade faster than lignin. But when we put them out in the forest soil, lignin degraded faster than cellulose! We've looked everywhere for a reason, but found none. The logic behind degradation is solid. There were no experimental mistakes we can think of. And lignin and cellulose were pure. So, should we trust the logic and ignore the evidence, or should we trust at the evidence and try and find different logic behind it?
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glaring problems with your logic #1:
ReplyDeletethere are ways that molecular bonds are broken that are not enzymatic
#2
ReplyDeletenot all molecular bonds are equal
#A
ReplyDeleteI also doubt your experimental results. First, doublecheck your starting material.
Molecular bonds in lignin don't break down spontaneously. It requires a bit of energy and thus need either energy input (like heat) or lowering of such requirement (enzymes). Lignin resists degradation because it almost randomly bonds with it's monomers in many different yet stable ways. The bonds require high energy input, or multiple enzymes to break, and so stays in polymer form longer. Cellulose on the other hand require fewer enzymes, and thus fewer kinds of microbes. We also checked the results and the starting material (even had the manufacturer check it). The point here is not if the experiment was done correctly but on the values of evidence and logic. Which should you trust more when they contradict? Logic or evidence?
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