Content area
Full text
World J Microbiol Biotechnol (2014) 30:14731484 DOI 10.1007/s11274-013-1565-0
ORIGINAL PAPER
Structural characterization of rhamnolipid producedby Pseudonomas aeruginosa strain FIN2 isolated from oil reservoir water
Jin-Feng Liu Gang Wu Shi-Zhong Yang
Bo-Zhong Mu
Received: 15 September 2013 / Accepted: 23 November 2013 / Published online: 3 December 2013 Springer Science+Business Media Dordrecht 2013
Abstract Biosurfactant-producing microorganisms inhabiting oil reservoirs are of great potential in industrial applications. Yet, till now, the knowledge about the structure and physicochemical property of their metabolites are still limited. The aim of this study was to purify and structurally characterize the biosurfactant from Pseudomonas aeruginosa strain FIN2, a newly isolated strain from an oil reservoir. The purication was conducted by silica gel column chromatography followed by pre-RP HPLC and the structural characterization was carried out by GCMS combined with MS/MS. The results show that the biosurfactant produced by FIN2 is rhamnolipid in nature and its four main fractions were identied to be Rha-C10-C10(46.1 %), RhaRha-C10-C10(20.1 %), Rha-C8-C10 (7.5 %) and Rha-C10-C12:1(5.5 %), respectively. Meanwhile, the rarely reported rhamnolipid congeners containing b-hydroxy fatty acids of
C6, C9, C10:1 and C11 were also proved to be present in the rhamnolipid mixture produced. The rhamnolipid mixture exhibited a strong surface activity by lowering the surface tension of distilled water to 28.6 mN/m with a CMC value of 195 mg/l.
Keywords Pseudonomas aeruginosa
Rhamnolipid Structure elucidation ESIMS
MS/MS GCMS
Introduction
Interest in biosurfactants has been progressively escalating in recent years. To date, researches on their structure and properties are receiving more and more attention. They are amphiphilic molecules with the hydrophilic part composed of sugars, amino acids, or polar functional groups like carboxylic acid groups and the hydrophobic part typically a bhydroxy fatty acyl group (Lang and Wullbrandt 1999; Lang 2002). The advantage of biosurfactants over their chemical counterparts lies in their low toxicity, higher biodegrad-ability, better environmental compatibility, high selectivity, specic activity at extremes of temperature, pH and salinity, and the ability to be synthesized from renewable feedstocks (Thanomsub et al. 2006). Because of their diverse structure and potential advantages, biosurfactants are widely used in many industries such as agriculture, food production, chemistry, cosmetics and pharmaceutics (Muthusamy et al. 2008; Banat et al. 2010).
The rhamnolipids from P. aeruginosa, are one of the most effective...