Can I add probiotics to my green smoothies?

Instead of buying expensive probiotics I've been trying to get my probiotics from food. I'm cultivating kefir and I eat rejuvinate brand salads. I have a daily green smoothie, I was wondering if I could add some powdered probiotic to this and make it alive too (increase the numbers of probiotics)? I can tolerate fruit now, so I usually put in berries into my smoothie, I assume this would be necessary anyway for the probiotics to eat the sugar? Is this even possible without milk, I like drinking my kefir seperate? If it is...
1.) What brand of probiotic should I use?
2.) Should I let it ferment for 24 hours unrefrigerated like kefir?
3.)How much probiotic powder for 48 ounces of smoothie?

Thanks in advance. Tweet