Table 6: Antibacterial spectrum of rhamnolipid mixtures produced by Pseudomonas strains.

MIC of rhamnolipid mixtures (g/ml)
8HCHAPA144014Commercial mixture

A. hydrophila LMG 2844-----
B. subtilis AM141.28026.3100-
E. faecalis V58341.2----
E. coli DH5Y20.6----
F. breve LMG 401182.5----
K. pneumoniae 050283165----
L. bozemanii ATCC 332170.26.21.65.27.8
L. dumoffii ATCC 332790.412.50.45.215.6
L. feeleii ATCC 350720.26.20.43.911.7
L. longbeachae ATCC 334840.412.53.37.913.1
L. micdadei ATCC 332180.033.13.33.915.6
L. pneumophila ATCC 33155 (Sg 3)0.212.53.315.88.8
L. pneumophila ATCC 33215 (Sg 6)0.26.20.47.93.9
L. pneumophila ATCC 33216 (Sg5)0.05251.67.919.5
L. pneumophila ATCC Baa74 130b0.0512.50.47.915.6
L. pneumophila Corby (Sg1)0.212.53.35.211.7
L. pneumophila Lens CIP 108286 (Sg1)0.412.51.610.511.7
L. ivanovii Li4pVS241.2----
L. monocytogenes EGDe ATCC BAA-67941.2----
P. aeruginosa LMG 1242-----
P. aeruginosa PA1482.5----
S. enterica J1882.5----
S. aureus ATCC 29213-80552.550-

-: no growth of inhibition was detected even with undiluted rhamnolipid mixture (660 µg/ml for the 8H mixture, 1610 µg/ml for the CHA extract, 105 µg/ml for the PA14 extract, 100 µg/ml for the 4014 extract, and 250 µg/ml for the commercial mixture).
Bacteria (106 CFU/ml) were incubated in BYE or BHI medium with two-fold dilutions of rhamnolipid mixtures. Results correspond to the MIC after incubation for 24h or 96 h at 37°C depending on the tested strain and are the mean of three independent experiments.
Bacterial strains were obtained from various culture collections: ATCC: American Type Culture Collection, CIP: Collection Institut Pasteur, France, and LMG: BCCM/LMG Bacteria Collection, Ghent University, Belgium. The Corby strain was kindly provided by the Centre National de Référence des Légionelles (Lyon, France). Other strains were from the laboratory culture collection. Sg: serogroup.