rhamnolipids Dotaz Zobrazit nápovědu
Rhamnolipid production by two non-pathogenic bacterial strains Acinetobacter calcoaceticus and Enterobacter asburiae, and established rhamnolipid producer Pseudomonas aeruginosa was investigated. Rhamnolipids were separated from supernatant and further purified by thin-layer chromatography. Mass spectrometry with negative electrospray ionization revealed rhamnolipid homologues varying in chain length and unsaturation. Tandem mass spectrometry identified mono-rhamnolipid and di-rhamnolipid homologues containing one or two 3-hydroxy fatty acids. Several media differing in carbon (sunflower oil, glycerol and sodium citrate), nitrogen (ammonium ions, nitrate) and phosphorus (total content) source, respectively, were tested to obtain enhanced rhamnolipid production. The best production (0.56g/l) was obtained when nitrate was used as a nitrogen source. Both strains produced rhamnolipids that exhibited excellent emulsification activity with aromatic and aliphatic hydrocarbons and several plant oils. Unlike P. aeruginosa the two strains, i.e. Acinetobacter and Enterobacter, are not pathogenic to humans.
- MeSH
- Acinetobacter calcoaceticus metabolismus MeSH
- Enterobacter metabolismus MeSH
- glykolipidy biosyntéza izolace a purifikace MeSH
- Pseudomonas aeruginosa metabolismus MeSH
- tandemová hmotnostní spektrometrie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
Rhamnolipids are extensively studied biosurfactants due to their potential in many industrial applications, eco-friendly production and properties. However, their availability for broader application is severely limited by their production costs, therefore the optimization of efficacy of their cultivation gains significance as well as the information regarding the physio-chemical properties of rhamnolipids resulting from various cultivation strategies. In this work, the bioprocess design focused on optimization of the rhamnolipid yield of Pseudomonas aeruginosa DBM 3774 utilizing the response surface methodology (RSM). Six carbon sources were investigated for their effect on the rhamnolipid production. The RSM prediction improved the total rhamnolipid yield from 2.2 to 13.5 g/L and the rhamnolipid productivity from 11.6 to 45.3 mg/L/h. A significant effect of the carbon source type, concentration and the C/N ratio on the composition of the rhamnolipid congeners has been demonstrated for cultivation of P. aeruginosa DBM 3774 in batch cultivation. Especially, changes in presence of saturated fatty acid in the rhamnolipid congeners, ranging from 18.8% of unsaturated fatty acids (carbon source glycerol; 40 g/L) to 0% (sodium citrate 20 g/L) were observed. This demonstrates possibilities of model based systems as basis in cultivation of industrially important compounds like biosurfactants rhamnolipids and the importance of detailed study of interconnection between cultivation conditions and rhamnolipid mixture composition and properties.
- Publikační typ
- časopisecké články MeSH
Rhamnolipids (RMLs) are a widely studied biosurfactant due to their high biodegradability and environmentally friendly production. However, the knowledge of the structure-property relationship of RMLs is imperative for the design of highly efficient applications. Aiming to a better understanding of it at a molecular level, we performed an automated search for low energy structures of the most abundant RMLs, namely, Rha-C10 , Rha-C10 -C10 , Rha-Rha-C10 and Rha-Rha-C10 -C10 and their respective C2 -congeners. Besides that, selected neutral metal complexes were also considered. We found that several low-energy congeners have internal hydrogen bonds. Moreover, geometries in "closed" conformation were always more stable than "open" ones. Finally, the energy diferences between open and closed conformations of K+ , Ni2+ , Cu2+ and Zn2+ complexes were found to be 23.5 kcal mol-1 , 62.8 kcal mol-1 , 24.3 kcal mol-1 and 41.6 kcal mol-1 , respectively, indicating a huge structural reorganization after the complex formation.
- MeSH
- glykolipidy chemie MeSH
- povrchově aktivní látky * chemie MeSH
- Pseudomonas aeruginosa * MeSH
- Publikační typ
- časopisecké články MeSH
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
In the food industry, the increasing antimicrobial resistance of food-borne pathogens to conventional sanitizers poses the risk of food contamination and a decrease in product quality and safety. Therefore, we explored alternative antimicrobials N-Acetyl-l-cysteine (NAC), rhamnolipids (RLs), and usnic acid (UA) as a novel approach to prevent biofilm formation and reduce existing biofilms formed by important food-borne pathogens (three strains of Salmonella enterica and two strains of Escherichia coli, Listeria monocytogenes, Staphylococcus aureus). Their effectiveness was evaluated by determining minimum inhibitory concentrations needed for inhibition of bacterial growth, biofilm formation, metabolic activity, and biofilm reduction. Transmission electron microscopy and confocal scanning laser microscopy followed by image analysis were used to visualize and quantify the impact of tested substances on both planktonic and biofilm-associated cells. The in vitro cytotoxicity of the substances was determined as a half-maximal inhibitory concentration in five different cell lines. The results indicate relatively low cytotoxic effects of NAC in comparison to RLs and UA. In addition, NAC inhibited bacterial growth for all strains, while RLs showed overall lower inhibition and UA inhibited only the growth of Gram-positive bacteria. Even though tested substances did not remove the biofilms, NAC represents a promising tool in biofilm prevention.
- MeSH
- acetylcystein farmakologie MeSH
- antibakteriální látky farmakologie MeSH
- antiinfekční látky farmakologie MeSH
- benzofurany farmakologie MeSH
- biofilmy účinky léků MeSH
- buněčné linie MeSH
- Escherichia coli účinky léků MeSH
- glykolipidy farmakologie MeSH
- kontaminace potravin prevence a kontrola MeSH
- lidé MeSH
- Listeria monocytogenes účinky léků MeSH
- mikrobiální testy citlivosti MeSH
- nemoci přenášené potravou farmakoterapie mikrobiologie MeSH
- potravinářská mikrobiologie metody MeSH
- Salmonella enterica účinky léků MeSH
- Staphylococcus aureus účinky léků MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Rhamnolipidy patří mezi významné povrchově aktivní látky mikrobiálního původu a mohou být použity v mnoha aplikacích. Přestože je produkce rhamnolipidů nákladnější, než syntéza chemických surfaktantů, jsou chemické surfaktanty postupně nahrazovány rhamnolipidy v aplikacích kladoucí důraz na netoxická a biologicky odbouratelná agens.
Rhamnolipids are important surface active compounds of microbial origin, which could be used in many areas. Although, at present are rhamnolipids more expensive than chemical surfactants, they slowly substitute chemical surfactants in applications with demand on using of non-toxic and biodegradable agents.
Novel rhamnolipid-producing strains of three thermophilic bacteria, Thermus sp., T. aquaticus and Meiothermus ruber were identified that have not been previously described as rhamnolipid producers. Rhamnolipids were extracted from supernatant and further purified by thin-layer chromatography. Mass spectrometry with negative electrospray ionization revealed 77 rhamnolipid homologues varying in chain length and unsaturation. Tandem mass spectrometry identified mono-rhamnolipid and di-rhamnolipid homologues containing one or two 3-hydroxy-fatty acids, saturated, monounsaturated or diunsaturated, even- or odd-chain, up to unusual long chains with 24 carbon atoms. The stereochemistry of rhamnose was L and that of 3-hydroxy-fatty acids was R, the position of double bonds in monoenoic acids was cis ω-9. All three strains produced a rhamnolipid that differs in structure from Pseudomonas aeruginosa rhamnolipids and exhibits excellent surfactant properties. Importantly, in comparison to P. aeruginosa both strains, i.e., Thermus and Meiothermus, are Biosafety level 1 microorganisms and are not pathogenic to humans.
- MeSH
- chromatografie na tenké vrstvě MeSH
- druhová specificita MeSH
- hmotnostní spektrometrie s elektrosprejovou ionizací MeSH
- lipidy analýza biosyntéza izolace a purifikace MeSH
- stereoizomerie MeSH
- Thermus klasifikace metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The aim of present work was to study chemical structures and biological activities of rhamnolipid biosurfactants produced by Pseudomonas aeruginosa MN1 isolated from oil-contaminated soil. The results of liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis revealed that total rhamnolipids (RLs) contained 16 rhamnolipid homologues. Di-lipid RLs containing C(10)-C(10) moieties were by far the most predominant congeners among mono-rhamnose (53.29 %) and di-rhamnose (23.52 %) homologues. Mono-rhamnolipids form 68.35 % of the total congeners in the RLs. Two major fractions were revealed in the thin layer chromatogram of produced RLs which were then purified by column chromatography. The retardation factors (R (f)) of the two rhamnolipid purple spots were 0.71 for RL1 and 0.46 for RL2. LC-MS/MS analysis proved that RL1 was composed of mono-RLs and RL2 consisted of di-RLs. RL1 was more surface-active with the critical micelle concentration (CMC) value of 15 mg/L and the surface tension of 25 mN/m at CMC. The results of biological assay showed that RL1 is a more potent antibacterial agent than RL2. All methicillin-resistant Staphylococcus aureus (MRSA) strains were inhibited by RLs that were independent of their antibiotic susceptibility patterns. RLs remarkably enhanced the activity of oxacillin against MRSA strains and lowered the minimum inhibitory concentrations of oxacillin to the range of 3.12-6.25 μg/mL.
- MeSH
- antibakteriální látky chemie izolace a purifikace farmakologie MeSH
- chromatografie kapalinová MeSH
- chromatografie na tenké vrstvě MeSH
- glykolipidy chemie izolace a purifikace farmakologie MeSH
- methicilin rezistentní Staphylococcus aureus účinky léků MeSH
- mikrobiální testy citlivosti MeSH
- oxacilin MeSH
- povrchově aktivní látky chemie izolace a purifikace farmakologie MeSH
- Pseudomonas aeruginosa chemie izolace a purifikace MeSH
- půdní mikrobiologie MeSH
- synergismus léků MeSH
- tandemová hmotnostní spektrometrie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The biofilms of filamentous-forming fungi are a novel and still insufficiently understood research topic. We have studied Aspergillus fumigatus, an ubiquitous opportunistic pathogenic fungus, as a representative model for a study of biofilm formation by filamentous fungi and for assessing the potential anti-biofilm activity of natural substances. The activity of antibiotic amphotericin B and selected natural substances: baicalein, chitosan and rhamnolipid was studied. The minimum suspension inhibitory concentrations (MIC) were determined and the biofilm susceptibility was investigated by determining the metabolic activity of sessile cells (XTT assay) and total biofilm biomass (crystal violet staining). Significant time-dependent differences in substances' anti-biofilm activity were observed. Images of A. fumigatus biofilm were obtained by Cellavista automatic light microscope and spinning disc confocal microscopy. Baicalein and rhamnolipid were not found as suitable substances for inhibition of the A. fumigatus biofilm formation, as neither of the substances inhibited the sessile cells metabolic activity or the total biofilm biomass even at tenfold MIC after 48 h. In contrast, chitosan at 10 × MIC (25 µg mL(-1)), suppressed the biofilm metabolic activity by 90 % and the total biofilm biomass by 80 % even after 72 h of cultivation. Amphotericin B inhibited only 14 % of total biofilm biomass (crystal violet staining) and 35 % of metabolic activity (XTT assay) of adherent cells under the same conditions. Our results therefore suggest chitosan as potential alternative for treating A. fumigatus biofilm-associated infections.
- MeSH
- amfotericin B farmakologie MeSH
- antifungální látky farmakologie MeSH
- Aspergillus fumigatus účinky léků fyziologie MeSH
- biofilmy účinky léků MeSH
- chitosan farmakologie MeSH
- flavanony farmakologie MeSH
- glykolipidy farmakologie MeSH
- mikrobiální testy citlivosti MeSH
- Publikační typ
- časopisecké články MeSH
The unflagging interest in the surfactants of biological origin, representing ecological alternatives to their synthetic counterparts, has enhanced R&D effort both to produce their new types and to resolve the bottlenecks of their commercialization. In this context, the rhamnolipids, offering a relatively large scale of potential applications, variety of congeners, low toxicity as well as stability towards the extremes of environment, logically attract attention. In this connection, the current state of knowledge concerning these compound exploitation, biosynthesis control and non-genetic factors affecting both production yield and final rhamnolipid product is surveyed.
