title: Structural characterization of a rhamnolipid-type biosurfactant produced by Pseudomonas aeruginosa MR01: enhancement of di-rhamnolipid proportion using gamma irradiation.
abstract: We previously reported that MR01, an indigenous strain of Pseudomonas aeruginosa, was able to produce a rhamnolipid-type biosurfactant. Here, we attempted to define the structural properties of this natural product. The analysis of the extracted biosurfactant by thin-layer chromatography (TLC) revealed the presence of two compounds corresponding to those of authentic mono- and di-rhamnolipid. The identity of two structurally distinguished rhamnolipids was confirmed by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. Liquid chromatography/mass spectrometry (LC/MS) of extracted biosurfactant revealed up to seventeen different rhamnolipid congeners. Further quantification showed di-rhamnolipids as the major compound (77.2%), while monorhamnolipids comprising a smaller proportion (22.8%) of MR01 biosurfactant. Rha-Rha-C10-C10 was verified as the major component of the MR01 biosurfactant (35.93%). Cytotoxic activity of MR01 biosurfactant against human cancer Hela cells showed an excellent inhibitory effect of 5μg/ml. An isolated mutant strain (MR01-C) created by Gamma ray irradiation demonstrated more than one and a half-fold biosurfactant production and activity compared with the parent strain. Analysis of the biosurfactant produced by MR01-C showed the magnitude of di-rhamnolipids in the sample increased up to 88.6% (∼15% higher than control) and the quantity of Rha-Rha-C10-C10 increased to 52.08% (∼45% higher than control).
authors: Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran.
authors: Tayebe B
authors: TB
authors: Lotfabad
authors: Habib
authors: H
authors: Abassi
authors: Reza
authors: R
authors: Ahmadkhaniha
authors: Reza
authors: R
authors: Roostaazad
authors: Fatemeh
authors: F
authors: Masoomi
authors: Hossein S
authors: HS
authors: Zahiri
authors: Gholamreza
authors: G
authors: Ahmadian
authors: Hojatollah
authors: H
authors: Vali
authors: Kambiz A
authors: KA
authors: Noghabi
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D002522:Chlorocebus aethiops; D004354:Drug Screening Assays, Antitumor; D004926:Escherichia coli / Q000187:drug effects; D005720:Gamma Rays; D006017:Glycolipids / Q000096:biosynthesis / Q000737:chemistry* / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000378:metabolism*; D013211:Staphylococcus aureus / Q000187:drug effects; D013329:Structure-Activity Relationship; D013501:Surface-Active Agents / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D014709:Vero Cells
chemical_list: D000970:Antineoplastic Agents; D006017:Glycolipids; D013501:Surface-Active Agents; C418382:rhamnolipid