I was once told that 70% ethanol is more effective in lysing bacteria than absolute ethanol. This was determined empirically.
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What passes from generation to generation of researchers is that 100% ethanol dehydrates instead of lysing, and some microrganisms might survive this. But if you end up with an actual reference for this, I'd be curious heheh.
As further evidence that 100% ethnaol and 70% ethanol have different properties, paper chromatography of black sharpie ink (or attempting to erase it form a plastic surface) will reveal that there is at least one component of black sharpie ink that is soluble in 100% ethanol but not 70% ethanol. 100% ethanol removes sharpie completely.
Maybe this has something to do with the way it interacts with the cell membrane.