-Most fungi require very high water availability (relative humidity),and rapidly dry out or senescencein dry conditions.
-Water activity (aw) = ps/pw (pure water = 1)
-DNA is denatured at aw= 0.55
◦Osmophiles 0.85, Xerophiles 0.80, Halophiles 0.75
-The xerotolerant fungi can growslowly, at water activity of 0.64.