Table 2.

Secondary screening of bacterial isolates for biosurfactant production.

No.	Isolate symbol	Drop collapse assay	Oil spreading assay (mm)	Surface tension	Emulsification index E24 (%)	BATH assay (%)
1	Z 4	+	—	62.67 ± 0.33	13 ± 1	20.33 ± 0.33
2	Z 5	+	48.33 ± 1.76	52	49 ± 1	66.33 ± 0.88
3	Z 7	+	33.33 ± 1.66	48.67 ± 0.67	43.66 ± 0.33	58.33 ± 0.88
4	Z 9	+	—	69.33 ± 0.33	—	—
5	Z 11	+	10.66 ± 0.66	67	—	12.66 ± 0.88
6	Z 14	+	7.66 ± 0.88	60.33 ± 0.33	—	15.33 ± 1.20
7	Z 25	+	30.33 ± 1.76	59	50.33 ± 0.33	74 ± 2.08
8	Z 31	+	77.66 ± 2.96	49	61	76.33 ± 0.88
9	Z 33	+	44.33 ± 0.33	52 ± 1	49.66 ± 1.45	64.33 ± 1.85
10	Z 34	+	—	68.33 ± 0.33	—	—
11	Z 35	+	23.33 ± 2.18	59	16.66 ± 0.33	30.33 ± 1.33
12	Z 36	+	10 ± 1.52	62.67 ± 0.33	10.33 ± 0.88	18.66 ± 1.76
13	Z 40	+	21.66 ± 0.33	61.67 ± 0.33	15	29.66 ± 0.88
14	Z 43	+	26.33 ± 0.33	60.67 ± 0.33	22.66 ± 0.33	56.66 ± 0.33
15	Z 44	+	—	61.33 ± 0.33	—	9.66 ± 0.66
16	Z 47	+	77.66 ± 0.33	44	64.66 ± 0.33	88.33 ± 2.18
17	Z 48	+	73.33 ± 1.20	49	50.66 ± 0.66	71.33 ± 0.88
18	Z 49	+	39.33 ± 0.33	61	47.33 ± 0.33	56.33 ± 1.20
19	Z 50	+	9.33 ± 1.66	59 ± 1.73	32.66 ± 1.20	57 ± 1
20	Z 51	+	3.66 ± 1.33	69	—	9.66 ± 1.20
21	Z 52	+	12.66 ± 1.20	67	9.66 ± 0.66	10.66 ± 0.33
22	Z 53	+	27.33 ± 1.85	64.67 ± 0.33	22.66 ± 0.88	11.66 ± 1.33
23	Z 54	+	48.33 ± 0.33	56.33 ± 0.33	44.33 ± 0.33	65.66 ± 1.85
24	Z 56	+	39 ± 1.52	61	48.66 ± 0.33	58.66 ± 0.33
25	Z 60	+	36.33 ± 0.33	59.33 ± 0.67	26.66 ± 0.33	51.33 ± 0.33
26	Z 66	+	—	65	—	14.33 ± 0.66
27	Z 71	+	38 ± 2.08	55.33 ± 0.67	37.66 ± 0.33	5.66 ± 0.66
28	Z 77	+	49.33 ± 0.33	50.33 ± 0.33	36.33 ± 0.66	61.66 ± 2.02
29	Z 80	+	22 ± 2.08	59	10.66 ± 0.33	30.66 ± 1.20

Data: mean ± SEM. The experiments were performed in three replicates. The bold values indicate that Z47 showed the higher E24% and the lowest surface tension, so, it is the best biosurfactant producer.