Table 3 Predicted interactions of the given factors depicted via severity index

1

NH₄H₂PO₄ (%) x Inoculum concen.

3 × 6

89.72

5

[1,2]

2

Temperature (°C) x Inoculum concen.

1 × 6

82.66

7

[1,2]

3

Temperature (°C) x Galactose (%)

1 × 4

82.06

5

[2,1]

4

Temperature (°C) x NH₄H₂PO₄ (%)

1 × 3

76.01

2

[2,1]

5

NH₄H₂PO₄ (%) x Galactose (%)

3 × 4

71.42

7

[2,1]

6

pH x Inoculum concen.

2 × 6

65.61

4

[2,2]

7

pH x Substrate length (m)

2 × 7

64.67

5

[1,2]

8

pH x Cupric sulphate (mM)

2 × 5

35.32

7

[1,2]

9

Substrate length (m) x Galactose (%)

2 × 4

34.38

6

[2,1]

10

NH₄H₂PO₄ (%) x Substrate length (m)

3 × 7

28.57

4

[2,2]

11

pH x NH₄H₂PO₄ (%)

2 × 3

23.98

1

[2,1]

12

Galactose (%) x Inoculum concen.

4 × 6

23.92

2

[1,2]

13

Temperature (°C) x Cupric sulphate (mM)

1 × 5

17.93

4

[2,2]

14

Temperature (°C) x Substrate length (m)

1 × 7

17.33

6

[1,2]

15

NH₄H₂PO₄ (%) x Cupric sulphate (mM)

3 × 5

10.27

6

[1,2]

16

Cupric sulphate (mM) x Substrate length (m)

5 × 7

5.15

2

[2,2]

17

Inoculum concen. x Substrate length

6 × 7

3.8

1

[2,2]

18

Temperature (°C) x pH

1 × 2

2.08

3

[2,2]

19

Galactose (%) x Cupric sulphate (mM)

4 × 5

2.06

1

[1,2]

20

Galactose (%) x Substrate length (m)

4 × 7

.28

3

[1,2]

21

Cupric sulphate (mM) x Inoculum concen.

5 × 6

.19

3

[2,2]