I found that there is no reason what so ever to use suger niether in
the starter nor the dough when making sourdough.
One of my starters was neglected in the fridge for about 4 months, the
whole thing froze and became dry as a rock. i was able to scarpe
something like half a gram of "wet" starter from it, fed it 50g water
50g flour and 12 hours later it was alive and kicking!
I guess the little critters love life the same way we humans love it
:-) survivle of the fittess...

Amit b