Fungi and other issues

 So don't keep the jar airtight.  Most starters can survive for a while in the fridge without refreshing.  Some have reported months.  You can still try to refresh your starter by taking a small amount of starter from the bottom of the jar. Usually it is best to scrape off what sounds like mold and  and  then scoop a little bit of starter out of the very bottom.  If your starter can breathe it will more likely get drier.

However to get all of the various bread raising microbes in the culture back up to speed you should refresh a few days before you bake.  Hopefully the fungi is just mold and will go away once you feed your culture air, flour and water.  I have let some cultures go for a while in the fridge and the hooch and mold is pretty fierce looking.  

Pictures might be helpful.

Croc gives more details in the following forum:  http://sourdough.com/forum/mold-sour-starter .   He suggests a clean sterilized jar too. 

Terri

Starter can really grow STUFF!  I've had pink mold and grey mold but never anything I'd call fungus.  So, I've learned to 1) use a new glass canister with straight sides and a loose-fitting glass lid (available at Target stores); 2) empty, wash and sterilize the jar with boiling water every two or three uses; 3) use boiled or distilled water when feeding; and 4) keep the starter in a stable temperature environment away from lid-lifting nose-pokers who might get something in it (the back of the fridge behind the salad is perfect). 

Previously, I'd used crockery pitchers with a saucer balanced on top.  The problem was that crockery can get minute cracks in the glaze which harbors contaminants even when doused with boiling water.  Also, the pitcher, having a spout, was a bit too open and moths would invade when I was warming it up. I've determined that purified water is the best bet.  We have great drinking water here, but there are all sorts of allowed microbes and chlorine in it.  Lastly, the stable temp environment keeps the starter on an even keel.  On the counter, near the stove and toaster ovens, it was prone to variations of cold (hubby likes to cut the heat drastically during the day) and heat far too frequently.  Also, my husband is not a clean as you go type and I found too many times an emptied cat food can sitting next to my starter.  Not good.  On hubby's defense, though, when it's his turn to make the bread, he has adopted cleaner habits and makes a mighty fine loaf! 

So far, the starter has been marvelously healthy and active with no ickies.  Cheers!