Phenanthrene solubilization
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Rhamnolipids are naturally occurring biosurfactants with a wide range of potential commercial applications. As naturally derived products they present an ecological alternative to synthetic surfactants. The majority of described rhamnolipid productions are single strain Pseudomonas spp. cultivations. Here we report rhamnolipids producing bacteria Acinetobacter calcoaceticus, Enterobacter asburiae and Pseudomonas aeruginosa that were cultivated separately and as mixed populations. The ratio and composition of rhamnolipid congeners was determined by tandem mass spectrometry with negative electrospray ionization. Mono-rhamnolipid and di-rhamnolipid homologues containing one or two saturated or monounsaturated 3-hydroxy fatty acids were found in all strains. Physiochemical characterization of rhamnolipids was evaluated by the critical micelle concentration determination, the emulsification test, oil displacement test and phenanthrene solubilization. Critical micelle concentrations of rhamnolipids produced by both single strain and mixed cultures were found to be very low (10-63 mg/l) and to correspond with saturated/unsaturated fatty acid content of rhamnolipid homologues. The rhamnolipids produced by all strains effectively emulsified crude petroleum in comparison with synthetic surfactants Tween 80 and sodium dodecyl sulfate (SDS). Good performance of phenanthrene solubilization was exhibited by rhamnolipids from E. asburiae. The single strain and co-cultures cultivations were proposed as a possible way to produce rhamnolipid mixtures with a specific composition and different physiochemical properties, which could be exploited in bioremediation of various hydrophobic contaminants.
- MeSH
- Acinetobacter calcoaceticus metabolismus MeSH
- Enterobacter metabolismus MeSH
- fenantreny chemie metabolismus MeSH
- glykolipidy chemie metabolismus MeSH
- hmotnostní spektrometrie s elektrosprejovou ionizací MeSH
- povrchově aktivní látky chemie metabolismus MeSH
- průmyslová mikrobiologie MeSH
- Pseudomonas aeruginosa metabolismus MeSH
- rozpustnost MeSH
- tandemová hmotnostní spektrometrie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Pseudomonads have been reported for their metabolic, nutritional and ecological versatility, which motivated us to prospect the metabolic profile of a lipolytic strain Pseudomonas aeruginosa SL-72. The strain SL-72 was found to produce high levels of lipase and pectinase (1,555.62 IU/mL and 1,490.33 IU/mL, respectively), esterase and amylase, besides low levels of xylanase, proteinase and cellulase. The strain also tested positive for different plant growth-promoting traits-production of ammonia, hydrogen cyanide, siderophores, phosphate solubilization, nitrate reduction and antifungal activity. The high levels of activity of aryl sulphatase, alkaline phosphatase and fluorescein diacetate hydrolase makes it a useful strain for enhanced nutrient cycling in soil. The strain SL-72 produced rhamnolipids, a biosurfactant and its production was enhanced when starch was used as carbon source (0.256 g/L) and utilized polycyclic hydrocarbon compounds viz. anthracene, phenanthrene, pyrene, fluorene and its mixture. The multifaceted nature of the culture illustrates its promise in bioremediation, industry, besides its use as an inoculant.