Fig. 2.

Three-dimensional response surface curve showing the effect of interactions of a pH and yeast extract b pH and l-tyrosine c pH and CuSO4d yeast extract and l-tyrosine e yeast extract and CuSO4fl-tyrosine and CuSO4

Three-dimensional response surface curve showing the effect of interactions of a pH and yeast extract b pH and l-tyrosine c pH and CuSO4d yeast extract and l-tyrosine e yeast extract and CuSO4fl-tyrosine and CuSO4