When cork is harvested the tree is not killed. Bark regrows and the cycle continues. Natural, beautiful cork. Anti-microbial, easy-to-roll, and good for the environment. Cork's anti-microbial properties come from a substance in cork called suberin. The science: Suberin is a cell wall-associated biopolymer found in specific cell types, such as root epidermis, root endodermis (including the Casparian band), bundle sheath cells and the periderm (cork) of woody species and underground organs (e.g., tubers). Suberin is unique and distinct from other non-carbohydrate cell wall bio polymers such as lignin and cutin for several reasons: (1) it is an assembly of two distinct polymeric domains, one poly(phenolic) and the other poly(aliphatic), (2) each domain has a unique chemical composition, and (3) both domains are present in the same cells. Suberin functions as a physical barrier, preventing water loss from the tissues it surrounds as well as providing protection against pathogens. It also forms a significant component of the wound healing process in plants; indeed the main model system to study suberin and the suberization process is the potato tuber. Upon wounding, tubers undergo a massive re-arrangement of metabolism, channeling significant metabolic energy into the formation of the phenolic and aliphatic monomeric precursors of suberin via two disparate metabolic pathways. (Western University)