Can Pichia pastoris (species of yeast used for recombinant protein) produce the non-protein amino acid Ornithine? Or does it express ornithine at all?
Yes, it contains arginase. Thise enzyme converts arginine to ornithine and is probably part of the urea cycle.
You might notice the arginase is listed as coming from Komagataella phaffii GS115, but this is just another (new?) name for Pichia.