Answer:
Bread purchased at various stores has preservatives in it to stave off mold, (Some producers use more preservatives than others). Mold grows more quickly when kept in warm, moist environments (like kitchen counter top). Also, be sure to let as much air out of the bag when sealing it. Keeping bread in the refrigerator will help it to last longer. You can put a few slices of bread in the microwave for about 5-10 seconds to "plump" it up without drying it out.