Location of mutation in E. Coli biosynthetic auxotroph

[Jeaneai]

I have isolated a mutant, streaked it onto pool plates and determined that it grows on minimal medium with the following additions: proline, arginine, ornithine, aspartic acid, proline, glutamic acid, inositol.

Since the mutant was mutagenized according to 99.9% killing etc. it should only be a single mutation, although I have stated in my write-up that I've considered the possibility of two separate mutations. However, I can't seem to pinpoint exactly where the mutation might be. I've been using EcoCyc to trace my way through the biosynthetic pathways connecting all of the above amino acids [inositol being the odd one out, not related to the others in any way], and I've been unable to locate an intermediate that explains growth on this plate and no other.

Can anyone help?