Table 1 The coded and actual values for the tested variables

X1

Malt extract

2

4

X2

Yeast extract

2

4

X3

Glucose

4

6

X4

Sucrose

2

4

X5

Salicylic acid

0.5

1.5

X6

Asparagine

1

3

X7

Glutamine

1

3

X8

Cysteine

1

3

X9

Tryptophan

2

4

X10

Glycine

2

4

X11

Phenylalanine

2

4

X12

Peptone

2

5

X13

pH

5

8

X14

Incubation time

10

15

X15

Sodium acetate

1

3

X16

Citric acid

1

3

X17

CaCl2

0.5

1.0

X18

NaCl

0.5

1.0

X19

Methyljasmonate

0.2

0.6