I am using a strain of Aspergillus terreus which mainly produces oxalic acid and a little of other organic acids, but it doesn't produce much of itaconic acid which is the metabolite of interest, even at pH 2. Considering the fact that low pH is one factor that minimizes undesirable by-product formation, what else can i do to ensure the strain produces more itaconic acid. The medium contains sufficient amounts of glucose and N-source