Mechanism-specific and whole-organism ecotoxicity of mono-rhamnolipids

Johann, Sarah; Seiler, Thomas‐Benjamin; Tiso, Till; Bluhm, Katharina; Blank, Lars M.; Hollert, Henner

doi:10.1016/j.scitotenv.2016.01.066

Cited by 68 publications

(38 citation statements)

References 45 publications

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“…Sha and co-workers 13 reported that di-RLs exhibit a higher antifungal activity against different plant pathogens when compared with mono-RLs, which exhibit only a weak inhibitory activity. Likewise, it was reported that mono-RLs inhibit the growth of A. niger only at very high concentrations (68 g/L) 28 . One of the mechanisms proposed for the biological activities of biosurfactants is their interaction with the phospholipid bilayer, which results in a detergent-like effect that disrupts the plasma membrane 29 .…”

Section: Resultsmentioning

confidence: 89%

Sodium chloride effect on the aggregation behaviour of rhamnolipids and their antifungal activity

Rodrigues

Gudiña

Teixeira

et al. 2017

Sci Rep

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In this work, the antifungal activity of rhamnolipids produced by Pseudomonas aeruginosa #112 was evaluated against Aspergillus niger MUM 92.13 and Aspergillus carbonarius MUM 05.18. It was demonstrated that the di-rhamnolipid congeners were responsible for the antifungal activity exhibited by the crude rhamnolipid mixture, whereas mono-rhamnolipids showed a weak inhibitory activity. Furthermore, in the presence of NaCl (from 375 mM to 875 mM), the antifungal activity of the crude rhamnolipid mixture and the purified di-rhamnolipids was considerably increased. Dynamic Light Scattering studies showed that the size of the structures formed by the rhamnolipids increased as the NaCl concentration increased, being this effect more pronounced in the case of di-rhamnolipids. These results were confirmed by Confocal Scanning Laser Microscopy, which revealed the formation of giant vesicle-like structures (in the µm range) by self-assembling of the crude rhamnolipid mixture in the presence of 875 mM NaCl. In the case of the purified mono- and di-rhamnolipids, spherical structures (also in the µm range) were observed at the same conditions. The results herein obtained demonstrated a direct relationship between the rhamnolipids antifungal activity and their aggregation behaviour, opening the possibility to improve their biological activities for application in different fields.

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Section: Resultsmentioning

confidence: 89%

Sodium chloride effect on the aggregation behaviour of rhamnolipids and their antifungal activity

Rodrigues

Gudiña

Teixeira

et al. 2017

Sci Rep

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“…Jeneil Biosurfactants Co. (Saukville, WI, USA) has successfully commercialized the use of RLs as active compound in the U.S. EPA approved biofungicide Zonix TM ( Muller et al, 2012 ). In a recent study by Johann et al (2016) involving daphnids and zebrafish embryos, mono-RLs have been described to cause comparable or lower levels of acute toxicity than chemical surfactants and no mutagenic effect confirming their safe use in agricultural and environmental applications.…”

Section: Discussionmentioning

confidence: 94%

Rhamnolipid Biosurfactant against Fusarium verticillioides to Control Stalk and Ear Rot Disease of Maize

et al. 2016

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Antifungal activity of rhamnolipids (RLs) has been widely studied against many plant pathogenic fungi, but not against Fusarium verticillioides, a major pathogen of maize (Zea mays L.). F. verticillioides causes stalk and ear rot of maize or asymptomatically colonizes the plant and ears resulting in moderate to heavy crop loss throughout the world. F. verticillioides produces fumonisin mycotoxins, reported carcinogens, which makes the contaminated ears unsuitable for consumption. In this study, the RL produced using glucose as sole carbon source was characterized by FTIR and LCMS analyses and its antifungal activity against F. verticillioides was evaluated in vitro on maize stalks and seeds. Further, the effect of RL on the mycelia of F. verticillioides was investigated by scanning electron microscopy which revealed visible damage to the mycelial structure as compared to control samples. In planta, treatment of maize seeds with a RL concentration of 50 mg l-1 resulted in improved biomass and fruiting compared to those of healthy control plants and complete suppression of characteristic disease symptoms and colonization of maize by F. verticillioides. The study highlights the potential of RLs to be used for an effective biocontrol strategy against colonization of maize plant by F. verticillioides.

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“…Rhamnolipids feature a low toxicity and an enhanced biodegradability in comparison to detergents with petrochemical origin (Maslin and Maier 2000; Johann et al 2016). Based on their surface active properties, they are used for bioremediation (Nguyen et al 2008), enhanced oil recovery (Wang et al 2007), and in cosmetic and food industries (Banat et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Novel insights into biosynthesis and uptake of rhamnolipids and their precursors

Wittgens

Kovačić

Müller

et al. 2016

Appl Microbiol Biotechnol

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The human pathogenic bacterium Pseudomonas aeruginosa produces rhamnolipids, glycolipids with functions for bacterial motility, biofilm formation, and uptake of hydrophobic substrates. Rhamnolipids represent a chemically heterogeneous group of secondary metabolites composed of one or two rhamnose molecules linked to one or mostly two 3-hydroxyfatty acids of various chain lengths. The biosynthetic pathway involves rhamnosyltransferase I encoded by the rhlAB operon, which synthesizes 3-(3-hydroxyalkanoyloxy)alkanoic acids (HAAs) followed by their coupling to one rhamnose moiety. The resulting mono-rhamnolipids are converted to di-rhamnolipids in a third reaction catalyzed by the rhamnosyltransferase II RhlC. However, the mechanism behind the biosynthesis of rhamnolipids containing only a single fatty acid is still unknown. To understand the role of proteins involved in rhamnolipid biosynthesis the heterologous expression of rhl-genes in non-pathogenic Pseudomonas putida KT2440 strains was used in this study to circumvent the complex quorum sensing regulation in P. aeruginosa. Our results reveal that RhlA and RhlB are independently involved in rhamnolipid biosynthesis and not in the form of a RhlAB heterodimer complex as it has been previously postulated. Furthermore, we demonstrate that mono-rhamnolipids provided extracellularly as well as HAAs as their precursors are generally taken up into the cell and are subsequently converted to di-rhamnolipids by P. putida and the native host P. aeruginosa. Finally, our results throw light on the biosynthesis of rhamnolipids containing one fatty acid, which occurs by hydrolyzation of typical rhamnolipids containing two fatty acids, valuable for the production of designer rhamnolipids with desired physicochemical properties.

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Mechanism-specific and whole-organism ecotoxicity of mono-rhamnolipids

Cited by 68 publications

References 45 publications

Sodium chloride effect on the aggregation behaviour of rhamnolipids and their antifungal activity

Sodium chloride effect on the aggregation behaviour of rhamnolipids and their antifungal activity

Rhamnolipid Biosurfactant against Fusarium verticillioides to Control Stalk and Ear Rot Disease of Maize

Novel insights into biosynthesis and uptake of rhamnolipids and their precursors

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