As a side note to food-grade plastic containers, I've noticed that some "nano-tech" plastics are being marketed as having superior food-preserving qualities, though I've not come across any statistcal science to support the claims, or have used them myself. The plastics are imbedded with silver particles, and are said to retard/inhibit bacterial and fungal growth: Article
Sharper Imgae product listed on Amazon

As has been mentioned, a ziplocked plastic bag that's been compressed to remove as much air as possible may be the best feild expedient version of a sterile, vacum sealed container.