Involved in the arginine deiminase pathway of fermentative arginine utilization. H2O + L-arginine = L-citrulline + NH4(+) Amino-acid degradation; L-arginine degradation via ADI pathway; carbamoyl phosphate from L-arginine: step 1/2. No induction in fermentatively grown cells. Belongs to the arginine deiminase family.