Yes, I believe one or more of the bacterial organisms responsible for sauerkraut fermentation can degrade cellulose, which is why sauerkraut is easy to digest (it doesn't give you the ...er... gut problems that, say, eating coleslaw does). Bear in mind that lactobacillus is not the only, or even first, microbe to be involved in cabbage fermentation. The process is also self-limiting, because at certain pH values, the microbes start to die off.