Citrus-smelling sourdough starter
I'm pretty confident you can get rid of that with the Ed Wood "washing" process. 


Stir hooch into starter. This stuff the microflora make to protect themselves.
Increase the volume 3-5 times with water
Stir until homogenous
Pour off 4/5ths of it
Tip in flour and stir until homogenous
If not a consistency you like then add more flour or water
Wait until it has risen double or triple
Repeat several times


Lactobacilli and yeast are just a lot more active than moulds when at room temperature, they will outcompete the mould spores. If there were a toxin you'd just be diluting it, but I've heard of people reviving prized cultures that had gone completely black.

Good luck!