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closeUse of Saline to Collect Samples -- Doesn't that invaliate results?
Posted by EmilyChatelet on 03 Jan 2013 at 20:49 GMT
Saline induces great stress in yeast (reduces their number, kills them). Doesn't this invalidate the test results?
RE: Use of Saline to Collect Samples -- Doesn't that invaliate results?
Evodia replied to EmilyChatelet on 07 Jan 2013 at 14:58 GMT
Saline was not used to collect samples. A saline solution was used to wash the grapes. The concentration of salt in the solution is low enough to create an somotic balance between the intracellular cytoplasm and the extracellular environment. This is to prevent yeast cells from either bursting or shrinking as a result of osmotic pressure. Physiological saline is commonly used to prepare serial dilutions if microbial populations. The concentation of NaCl in such a solution is below 1% w/v and should not generate stress or kill the yeast cells. Most of the yeast associated with grapes are exposed to 10 - 25% w/v sugars in grape must when the grapes are crushed for winemaking, which is far higher than the 1% in the saline solution.