Subject: Why does mold form on rye bread faster than it does on white or wheat?

I am doing an experiment on mold. I know what mold is and how it comes 
about but i was wondering why does it form faster on rye bread than wheat 
or white. I did an experiment with three different slices of bread  with 
rye, wheat, and white being my samples. I used a cotton swab to put dust 
on all three samples and placed them in a plastic bag and let the process 
of mold begin. I noticed it started growing on the rye bread first and now 
i was wondering why was this does it have to do with the preservatives 
used in each bread?

Re: Why does mold form on rye bread faster than it does on white or wheat?