Heterologous production of Pseudomonas aeruginosa EMS1 biosurfactant in Pseudomonas putida.
A new bacterial strain isolated from activated sludge, identified as Pseudomonas aeruginosa EMS1, produced a biosurfactant when grown on acidified soybean oil as the sole carbon source. An optimum biosurfactant production of 5 g/L was obtained with the following medium composition: 2% acidified soybean oil, 0.3% NH4NO3, 0.03% KH2PO4, 0.03% K2HPO4, 0.02% MgSO4.7H2O and 0.025% CaCl2.2H2O, with shaking at 200 rpm for an incubation period of 100 h at 30 degrees C. The production of the biosurfactant was found to be a function of cell growth, with maximum production occurring during the exponential phase. Hemolysis of erythrocytes and thin-layer chromatography studies revealed that the secreted biosurfactant was rhamnolipid. To overcome the complex environmental regulation with respect to rhamnolipid biosynthesis, and to replace the opportunistic pathogen P. aeruginosa with a safe industrial strain, attempts were made to achieve rhamnolipid production in a heterologous host, Pseudomonas putida, using molecular cloning of rhlAB rhamnosyltransferase genes with the rhlRI quorum sensing system, assuming that a functional rhamnosyltransferase would catalyze the formation of rhamnosyl-6-hydroxydecanoyl-6-hydroxydecanoate (mono-rhamnolipid) in P. putida. It was shown that rhamnolipid can be produced in the heterologous strain, P. putida, when provided with the rhamnosyltransferase genes.
Cha
Misun
M
School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742, Republic of Korea.
Lee
Naeun
N
Kim
Minju
M
Kim
Mia
M
Lee
Sangjoon
S
D001483:Base Sequence; D017931:DNA Primers; D011550:Pseudomonas aeruginosa / Q000378:metabolism*; D016958:Pseudomonas putida / Q000378:metabolism*; D013500:Surface Tension; D013501:Surface-Active Agents / Q000378:metabolism*
D017931:DNA Primers; D013501:Surface-Active Agents