about the storage of marine Vibrios - (Sep/28/2012 )

Hi, everyone! I've met a problem that many marine vibrio strains of mine failed to survive after several months' storage (less than half of a year).

My storage conditions is 20% glyceral at -40℃. Could you tell me some better ways to store those marine vibrio?

I had no problems with 15% glycerol at -80, but I don't know how sensitive they are to higher glycerol and higher temperature.