Can I use fermented milk product as starter culture?
Yes. Whey, primarily a byproduct of cheese-making (but also from yogurt, kefir &amp;c), can be used to inoculate a variety of ferments. In the book The Art of Fermentation, for example, there are instructions for using it as a starter for fermenting fruit, vegetable, seed/nut and sour tonic beverage ferments. The most important thing is that the whey not have been heated (most likely in cheese-making) to a point high enough to kill the bacteria present. 

My experience is limited (I usually drink my whey or put it in a soup), but I'd imagine you wouldn't want to use anything milkier than whey to ferment veggies with. Fermented milk itself can be used to propagate a mother-culture (e.g. with sour cream, buttermilk, yogurt &amp;c.) but I'm guessing you wouldn't really want to dump these into vegetables.