Many people prefer to keep bread at room temperature, but refrigeration means you won't have to throw out as much bread due to mould. Mold is caused by several factors.
Millions of invisible mould spores inhabit the air around you. These spores swirl around in the dust in your home. When you leave bread out or the refrigerator open for any amount of time, mould spores float onto your bread.
Mold belongs to the fungi family. Fungi contain no chlorophyll, so it can't draw energy directly from the sun. Instead mould fungi derives nutrients from other food sources. The ingredients in bread, along with a low moisture index, create the perfect environment for the mould to settle on, grow and reproduce.
Warmth & Nutrients
Mold thrives in warm, moist conditions which is why bread that is not refrigerated will show signs of mould before bread in the refrigerator. Mold eventually will grow on bread that is refrigerated because the bread provides a good source of nutrients for the mould spores. However, the colder temperatures do retard the growth of mould on bread.