The world's biggest seller of beverages has begun using a new bottle partially made from a plant-based material that, unlike petroleum-based plastic, is biodegradable. The new bottles for Coca-Cola, Coca-Cola Light, and Coke Zero still contain only 30 percent sugar cane-based material, The Wall Street Journal reports. But the soft-drink giant sees what it calls the "plantbottle" as the first step in an evolution of its packaging.