Table 1.

Screening for biosurfactant production: oil spreading assays, drop collapse assay and emulsification activity of the isolates

No.	Strain	Oil spreading	Drop collapse	Emulsification index
1	NA3	++	+++	38.5
2	MN1	+	++	6.94
3	MN3	++	+++	36.4
4	TBH2	+	+	8.5
5	TMN2	+	+	7.6
6	TNA2	++	+	5.2
7	TTB1	+	+	9.2

NA3, P. stutzeri; MN1, P. stutzeri; MN3, A. baumannii; TBH2, P. aeruginosa; TMN2, C. Caeni; TNA2, Pseudomonas sp.; TTB1, A. xylosoxidans

Oil spreading assay: ‘+’—oil spreading with a clear zone of 0.5–1.0 cm—‘++’—oil spreading with a clear zone of 1.5–2.0 cm—‘+++’—oil spreading with a clear zone of 2.0–3.0 cm

Drop collapse assay: ‘+++’—drop collapse within 1 min—‘++’—drop collapse after 1 min and ‘+’—drop collapse after 2 min of biosurfactant addition