About a week ago I started reviving some yeast from bottle dregs from a previous batch of home brew. I was building up the starter with plans to brew this weekend, but unfortunately was unable to get the grains I needed from the LHBS (shop is currently closed due the hurricane force winds that just went through the midwestern US and more or less knocked out entire cities). My question is, what is the best way to store this starter to keep the yeast as healthy as possible for a future brew? It's currently sitting in my fridge in the starter wort that had just finished fermenting. Is it okay in that, or should I pour of the wort and cover with sterile water?