it illegal to brew beer with such fillers in Germany?
Yes they have a beer purity law - the Reinheitsgebot - which requires only malt and hops (or in the case of Weissbier, wheat is allowed) to be used in the production.
http://en.wikipedia.org/wiki/Reinheitsgebot
Of course that doesn't necessarily mean all German beer is bottle conditioned but even with the pasteurised variety it's nice to know what you're drinking has no evil adjuncts in the recipe.