sorry , i come from a wine making back ground with only three AG brews below the belt, several hundred kits, but you get a fresh yeast with every tin so never botherd.
all i would have to do is just replace the white sugar with a simple wort instead, maybe even go as far as buying a cheap can or bottle of it just for yeasts how about dried malt extract or liquid extract from a ten pound kit tin
as for the yeast acting differently with different sugars, can anyone back this up with a credible link to a yeast site or proven back ups, sounds a little far fetched but it could be true i know nothing of beer yeasts or lager yeasts