Bacteria require several things  in order to thrive and grow: oxygen, sunlight, water, nutrients and substrate on which to form. The minerals found in granite are toxic to most bacteria. As a result, granite is not habitable environment for bacteria to live and grow. The Marble Institute of America has conducted independent research on bacteria growth on all countertop materials. Granite ranked first in cleanability and was second only to stainless steel in inhibiting bacteria growth.