Niger is considered to be [From Google] "a fungus... It causes a disease called black mold on certain fruits and vegetables such as grapes, onions, and peanuts, and is a common contaminant of food" Also common to places indoors and is usually associated with invasive pulmonary aspergillosis."
The mould also contaminates food. Again, this apparently tends to be found indoors; such as in damp buildings. I'm not sure if any of this is useful but I thought I would give it a try anyway :)