|MadSci Network: Microbiology|
I can't find anyone who knows the answer to your question, but there are a few considerations, and simple experiments that would allow you to sort this out. 1. By centrifuging you are forcing those things that are more dense than the sludge solution to sink, but those things that are less dense than the sludge solution to RISE. So if you have a gas pocket that is moving very very slowly upwords and then centrifuge, it will now move up more quickly. This is how bouyant density centrifugation works. How accurately can you determine the volume of the sludge before and after centrifugation? The weight may also decrease if you can determine that, but very slightly as you are dealing with gases. 2. A simple experiment would be to dope the sludge with lysozyme and determine if it makes a difference. Lysozyme would degrade the cell wall and make more of the bacteria fragile. 3. You said 2000g. Frankly that isn't much. I centrifuge E. coli at 15000g without any problem. With H. influenzae which is more fragile I centrifuge it at 3000g. Good Luck! David Beck Madsci Admin
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