Disable bridge module insert?

I have Fedora 20 setup with default kernel configuration, where bridge feature is enabled as a module (CONFIG_BRIDGE=m), and the bridge module loads as the system starts. I don't understand who initiates it, since I have not found anything about bridge.ko in /etc/sysconfig/modules/*. However it ends up in the memory and every time I have to 'rmmod' it. I would like to prohibit loading of the bridge.ko on the start up, yet I still want to manually load/unload bridge.ko whenever necessary. I know it is possible to use the blacklist feature in /etc/modprobe.d/blacklist.conf, but can anybody point out who is loading bridge.ko in default setup of Fedora 20?