Table 1.
Antibacterial activity of the biosurfactant extracts (1.00 mg mL−1) against a panel of Gram-negative and Gram-positive bacterial isolates
| Organism (strain number) | Source | Antibacterial inhibition zone diameter (mm) ± SD | |
|---|---|---|---|
| Surfactin extract (0.26 ± 0.09 mg mL−1) |
Rhamnolipid extract (1.12 ± 0.08 mg mL−1) |
||
| Gram-negative target organism | |||
| Escherichia coli (ATCC 417373) | ATCC | 13 ± 0 | 13.5 ± 0.4 |
| E. coli (ATCC 13706) | ATCC | 10 ± 0 | 29.3 ± 0.9 |
| Enteroinvasive E. coli (ATCC 43892) | ATCC | 15 ± 0 | 22.7 ± 2.1 |
| GEnteropathogenic E. coli (B170) | ATCC | 18.3 ± 0.5 | 20.3 ± 0.5 |
| Enterohaemorhagic E. coli (O157:H7) | ATCC | 13.7 ± 0.5 | 13.7 ± 0.5 |
| Enterotoxigenic E. coli (H10407) | ATCC | 17.7 ± 1.2 | 13 ± 0 |
| Enteroaggregative E. coli (3591-87) | ATCC | 12.3 ± 0.5 | 24.3 ± 1.2 |
| Klebsiella pneumoniae (ATCC 10031) | ATCC | 14 ± 1.6 | 13.5 ± 0.5 |
| Salmonella typhimurium (ATCC 14028) | ATCC | 25.3 ± 1.2 | 20.3 ± 0.5 |
| Serratia marcescens (ATCC 13880) | ATCC | 12.7 ± 0.9 | 14 ± 0 |
| K. pneumoniae (P2) | Clinical | 13 ± 0.8 | 11.7 ± 0.9 |
| K. pneumoniae (P3) | Clinical | 13.3 ± 0.2 | 8.3 ± 0.5 |
| Salmonella enterica (SE19) | Environment | 12.5 ± 0.5 | 14 ± 0 |
| Acinetobacter sp. (F1S6) | Environment | 12.3 ± 0.5 | 13 ± 1.4 |
| Serratia sp. (SM14) | Environment | 11.7 ± 0.9 | 14.3 ± 1.2 |
| Serratia sp. (L8) | Environment | 12.5 ± 0.5 | 9.8 ± 0.8 |
| Enterobacter sp. (E11) | Environment | 11.3 ± 0.5 | 13 ± 0.8 |
| Enterobacter sp. (E22) | Environment | 14.2 ± 0.6 | 13 ± 0.8 |
| E. coli (K4CCA) | Environment | 14.5 ± 0.5 | 17.7 ± 1.9 |
| K. pneumoniae (k2a) | Environment | 15.3 ± 0.5 | 13.7 ± 0.5 |
| Gram-positive target organism | |||
| O Staphylococcus aureus (ATCC 25923) | ATCC | 14.7 ± 0.5 | 13.7 ± 0.5 |
| B. cereus (ATCC 10876) | ATCC | 10.3 ± 0.5 | 13 ± 0.8 |
| B. cereus (LMG 13569) | ATCC | 13 ± 0.8 | 17 ± 1.4 |
| Enterococcus faecalis (S1) | Clinical | 18.7 ± 0.9 | 10.7 ± 0.5 |
| Enterococcus faecalis (S2) | Clinical | 18.3 ± 1.2 | 21.7 ± 2.4 |
| G,O,P,TMRSA (Xen 30) | Clinical | 15.3 ± 0.5 | 13.3 ± 0.5 |
| Bacillus cereus (ST18) | Environment | Inactive | 22.3 ± 0.9 |
| Enterococcus sp. (C513) | Environment | 12.3 ± 0.5 | 15.7 ± 0.5 |
| Micrococcus sp. (AQ4S2) | Environment | 14 ± 0 | 14 ± 1 |
| S. aureus (C2) | Environment | 11.5 ± 0.5 | 14 ± 0 |
| S. aureus (C3) | Environment | 12 ± 0 | 11 ± 0 |
The surfactin and rhamnolipid extracts were observed to be at 32.8 and 34.4% purity, respectively
Values are the means ± standard deviations (SD) of triplicate measurements; ATCC American Type Culture, O resistant to Oxacillin, G resistant to Gentamicin, T resistant to Tetracycline, P resistant to Penicillin G