Stagnant air in combination to high humidity levels in basements and storage rooms can easily lead to fungal growth. This is the reason that generally a combination of air flow and dehumidification is used in the drying process not just one or the other.
This basement had a previous water damage that was not fully dried out and the stagnant air let to growth on the drywall and contents.
This homeowner called SERVPRO of Springfield to help them with their issue. The drywall was removed and the contents had to be disposed. The underlying structure was cleaned and dried before new drywall could be hung and painted.