Structural characterization of a rhamnolipid-type biosurfactant produced by Pseudomonas aeruginosa MR01: Enhancement of di-rhamnolipid proportion using gamma irradiation
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- 作者：Tayebe B. Lotfabad ; Habib Abassi ; Reza Ahmadkhaniha ; Reza Roostaazad ; Fatemeh Masoomi ; Hossein S. Zahiri ; Gholamreza Ahmadian ; Hojatollah Vali ; Kambiz A. Noghabi
- 关键词：Rhamnolipid ; Gamma irradiation ; Monorhamnolipid ; Di-rhamnolipid ; Pseudomonas aeruginosa MR01
- 刊名：Colloids and Surfaces B: Biointerfaces
- 出版年：2010
- 出版时间：1 December 2010
- 年：2010
- 卷：81
- 期：2
- 页码：397-405
- 全文大小：502 K
文摘
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 5 μg/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).