Table 3.

Predicted interactions of the given factors depicted via severity index

Sl. No:	Interacting factor pairs (Order based on SI)	Columns	SI (%)	Col.	Opt.
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]

Columns: Column locations to which the interacting factors are assigned, SI%: Interaction severity index, Col: Column that should be reserved if this particular interaction is to be studied, Opt.: indicates factor levels desirable for the optimum condition