Table 1.

Statistical analysis of the model by Plackett–Burman design for l-DOPA production

Source	Sum of Squares	df	Mean square	F value	P value Prob > F
Model	0.101625	4	0.025406	31.7145	0.0001*
X1-pH	0.008427	1	0.008427	10.51935	0.0142*
X3-yeast extract	0.01068	1	0.01068	13.33216	0.0082*
X7-l-tyrosine	0.072075	1	0.072075	89.97058	<0.0001*
X8-CuSO4	0.010443	1	0.010443	13.0359	0.0086*
Residual	0.02175	7	0.02175
Cor total	0.005608	12

P < 0.05, * Significant P value