title: Rhamnolipids production by multi-metal-resistant and plant-growth-promoting rhizobacteria.
abstract: The biosurfactant-producing Pseudomonas aeruginosa A11, with plant-growth-promoting (PGP) and multi-metal-resistant (MMR) features was isolated from the rhizosphere of a wild plant Parthenium hysterophorus. The strain A11 was able to utilize glycerol as a carbon source and produce 4,436.9 mg/L of biosurfactant after 120 h of incubation. The biosurfactants was characterized as rhamnolipids (RLs) by thin layer chromatography, Fourier transform infrared spectroscopy, nuclear magnetic resonance, and liquid chromatography-mass spectrometry analysis. Eight different RLs congeners were detected with RhaRhaC₁₀C₁₀ being most abundant. The purified rhamnolipid, dirhamnolipid, and monorhamnolipid reduced the surface tension of water to 29, 36, and 42 mN/m with critical micelle concentration of 83, 125, and 150 mg/L, respectively. The strain A11 demonstrated resistance against all the metals detected in rhizosphere except Hg and Ni. The strain A11 also possessed plant-growth-promoting features like siderophores, hydrogen cyanide, catalase, ammonia production, and phosphate solubilization. The dirhamnolipids formed crystals upon incubation at 4 °C, thus making separation of dirhamnolipids easy. Biosurfactant-producing ability along with MMR and PGP traits of the strain A11 makes it a potential candidate for application in the bacterial assisted enhancement of phytoremediation of heavy-metal-contaminated sites.
authors: Institute of Microbial Technology, Sector 39 A, Chandigarh 160036, India.
authors: Anil Kumar
authors: AK
authors: Singh
authors: Swaranjit Singh
authors: SS
authors: Cameotra
mesh_terms: D019659:Asteraceae / Q000187:drug effects / Q000254:growth & development* / Q000382:microbiology*; D006017:Glycolipids / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D008670:Metals / Q000493:pharmacokinetics* / Q000494:pharmacology; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development* / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification / Q000502:physiology*
chemical_list: D006017:Glycolipids; D008670:Metals; C418382:rhamnolipid