Rhamnolipid Research Papers - Academia.edu (original) (raw)

This study evaluates the single and combined usage of chitosan (2% w/v) and rhamnolipid (2% w/v) as edible coatings to extend the shelf life of sweet oranges stored at 25 °C for 8 weeks. Physiochemical, microbial and sensory analysis of the oranges was conducted during ambient storage. The combined treatment of chitosan and rhamnolipid coating on oranges significantly delayed a loss in chlorophyll quality, malondialdehyde, weight loss, soluble solids content, titratable acidity, vitamin C content and delayed the loss of firmness during the 8 weeks of storage. The combined chitosan-rhamnolipid coating significantly increased the activities of superoxide dismutase, catalase, and peroxidase, as well as inhibited the generation of superoxide free radicals and the growth of mesophilic bacteria, yeast and mould.

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- Chitosan, Citrus Fruits, Rhamnolipid, Edible Coating with Natural Extract

Rhamnolipids are the best studied glycolipids having excellent surface activity. Their utilization in various application areas of environment, health, food, cosmetic, oil industry etc., havemade it the potential candidates that could replace the chemically synthesized surfactants becausethese are derived from the natural source, in a pure form and they have low toxicity levels. The production of rhamnolipids dependent on several environmental and nutritional factors and thehighest yield of rhamnolipids are estimated at 6 g/L with specific parameters. Effects of multivalentions, nutritional factors and environmental conditions are described by many researchers to find outits enhanced production (Desai and Banat, 1997). In this mini review, some nutritional,environmental and compositional factors are studied and estimated that how the production of rhamnolipids enhanced and which kind of effects these factors have on its production.

A local cultivar of sweet orange namely ‘Agege sweet’ constitutes a larger percentage among many citrus varieties planted in Nigeria, but there is a major setback in terms of extending its post-harvest shelf life. This work was designed to assess the effectiveness of a rhamnolipid coating to preserve the quality attributes of Agege sweet orange fruit during 8 wk ambient storage compared with that of Aloe vera gel. Petri plates were supplied with different treatments (volume per volume, v/v) of Aloe vera gel (0%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%) or rhamnolipid (0%, 0.25%, 0.5%, 1.0%, 1.5 %, 2.0%) and oranges were inoculated with a spore suspension of P. digitatum NSP01 spores. The solutions of rhamnolipid (2%) and Aloe vera gel (2%) were evaluated for their biocontrol activity on P. digitatum NSP01. The fruits were stored for 8 wk at 25ºC. The lesion area, firmness, and chemical composition were assessed. The oranges coated with Aloe vera gel and rhamnolipid significantly (p < 0.05) prevented loss in firmness, total soluble solids and titratable acidity and reduced the decay caused by P. digitatum NSP01. Therefore, the newly formulated rhamnolipid-Aloe vera edible coating could serve as a permanent substitute for chemical fungicides used in the management of diseases and pests affecting agricultural productivity.

- by Israel Afolabi
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- Rhamnolipid, Edible Coating with Natural Extract, Orange, Edible Coatings

Background: Rhamnolipids are hydrophilic glycolipids, often classified as biosurfactants. They are produced by different bacterial species. Rhamnolipids are extensively studied in biological research because of their interesting features like antimicrobial, antifungal, and antiviral activities. Materials and Methods: To study the antimicrobial effect of rhamnolipid, we conducted a crosssectional study on the eight different pathogenic bacterial strains from November 2019 to June 2020. These bacterial strains were isolated from the organic compost. Both disk diffusion and broth microdilution methods were used to evaluate the inhibitory effects of rhamnolipids on these pathogenic bacteria. Also, protease and amylase enzyme activities were evaluated in these eight bacterial isolates. Results: For Bacillus stearothermophilus, within the area of 31.5 mm, no growth was observed, hence proving the inhibitory effect of rhamnolipid. After calculating the Minimum Inhibitory (MIC) and Minimum Lethal Concentrations (MLC) for each bacterial strain, it has been found that the studied bacteria were more susceptible to rhamnolipids than most of the antibiotics. Strains were also quantified for their enzymatic activity of proteases and amylases. The bacterial strains of Bacillus stearothermophilus, Brevibacillus brevis, Bacillus licheniformis, and Bordetella petrii showed maximum protease activity. Whereas Escherichia coli, Enterococcus faecalis, Enterobacter aerogenes, and Pseudomonas aeruginosa showed high amylase activity. Conclusion: Rhamnolipids can be used as a potential antimicrobial agent for treatment of infections.

- by Research in Molecular Medicine (RMM)
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- Protease, Surfactant, Rhamnolipid, Antimicrobial

In this research, previously identified Pseudomonas aeruginosa (IMBB Strain)was re-streaked onto a fresh nutrient agar slants and stored at 4˚ C for further use. Ironlimited mineral salt medium with the prescribed composition was used for the productionof biosurfactants. Three different salts, namely ferrus chloride, ferrus sulfate and ferrousammonium sulfate, were selected to analyze their effect on rhamnolipid production. Theexperiments were designed in three batches containing varying concentrations of ferrouschloride, ferrous sulfate and ferrous ammonium sulfate with one control flask. Theproduced rhamnolipid was detected physically and chemically by surface tensionmeasurement and Orcinol assay, respectively. There was highest yield of Rhamnolipid of 3.81 g/L when the medium of Manitol was varied with 0.008 g/L of ferrous sulfate. TheRhamnolipid production using 0.004 g/L ferrous chloride was estimated as 1.85 g/L.

- by Dr. Muhammad Irfan-Maqsood
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- Biodegradation, Biosurfactant, Rhamnolipid, Iron containing compounds
- by Pattanathu Rahman
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- Rhamnolipid

Quorum sensing (QS) has received significant attention in the past few decades.
QS describes population density dependent cell to cell communication in bacteria
using diffusible signal molecules. These signal molecules produced by bacterial
cells, regulate various physiological processes important for social behavior and
pathogenesis. One such process regulated by quorum sensing molecules is the
production of a biosurfactant, rhamnolipid. Rhamnolipids are important microbially
derived surface active agents produced by Pseudomonas spp. under the control of
two interrelated quorum sensing systems; namely las and rhl. Rhamnolipids possess
antibacterial, antifungal and antiviral properties. They are important in motility, cell
to cell interactions, cellular differentiation and formation of water channels that are characteristics of Pseudomonas biofilms. Rhamnolipids have biotechnological
applications in the uptake of hydrophobic substrates, bioremediation of contaminated
soils and polluted waters. Rhamnolipid biosurfactants are biodegradable as compared
to chemical surfactants and hence are more preferred in environmental applications.
In this review, we examine the biochemical and genetic mechanism of rhamnolipid
production by P. aeruginosa and propose the application of QS signal molecules in
enhancing the rhamnolipid production.

- by Dr. Devendra Dusane
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- Biosurfactant, Biofilm, Pseudomonas, Quorum Sensing

- by Isaac Adejumo
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- Chitosan, Citrus Fruits, Rhamnolipid, Edible Coating with Natural Extract
- by Vayalam P Venugopalan
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- Engineering, Microbiology, Technology, Biofilms
- by Prof. G Girija Sankar
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- Bioengineering, Chemistry, Molecular Biology, Biotechnology

Rhamnolipid (RL) is a surfactant biosynthesized by Pseudomonas aeruginosa strains. The RL feasibility as a high‐efficient emulsifier in increasing the physical stability of sesame oil (SO)‐based beverage emulsions formed by the ultrasound‐assisted emulsification process was studied. The concentration of SO (2.02%–6.98% wt/wt), and RL (0.49%–1.51% wt/wt) was adequately optimized based on the analysis of physical stability, turbidity loss rate (TLR), size index, density, and viscosity characteristics using the central composite rotatable design‐response surface methodology. The overall optimum region to attain the highest stability (92.64%), viscosity ratio (0.338), and density (1.017 g/cm3), and the lowest TLR (0.216 Ǻ/day) and size index (0.240) based on the adequate second‐order polynomial models (R2 = 0.956–0.991) was obtained at the combined level of 2.75% (wt/wt) SO and 0.662% (wt/wt) RL. No significant difference between the observed and predicted values fitted to second‐order polynomial models was found. RL as an efficient biosurfactant can stabilize food‐grade emulsion systems.

- by Safoora Karimi
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- Chemistry, Ultrasound, Emulsifier, Rhamnolipid
- by Pattanathu Rahman
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- Engineering, Microbiology, Technology, Biofilms

Removal of detrimental biofilms from surfaces exposed in the marine environment remains a challenge.
A strain of Bacillus pumilus was isolated from the surface of titanium coupons immersed in seawater in the
vicinity of Madras Atomic Power Station (MAPS) on the East coast of India. The bacterium formed extensive
biofilms when compared to species such as Bacillus licheniformis, Pseudomonas aeruginosa PAO1 and
Pseudomonas aureofaciens. A commercially available rhamnolipid was assessed for its ability to inhibit
adhesion and disrupt pre-formed B. pumilus biofilms. The planktonic growth of B. pumilus cells was inhibited
by concentrations >1.6mM. We studied the effect of various concentrations (0.05–100mM) of the
rhamnolipid on adhesion of B. pumilus cells to polystyrene microtitre plates, wherein the effectiveness
varied from 46 to 99%. Biofilms of B. pumilus were dislodged efficiently at sub-MIC concentrations, suggesting
the role of surfactant activity in removing pre-formed biofilms. Scanning electron microscopy
(SEM) confirmed the removal of biofilm–matrix components and disruption of biofilms by treatment
with the rhamnolipid. The results suggest the possible use of rhamnolipids as efficient anti-adhesive and
biofilm-disrupting agents with potential applications in controlling biofilms on surfaces.

- by Dr. Devendra Dusane and +1
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- SEM, Biofilm, Pseudomonas, Bacillus

Halophilic bacterium, <i>Pseudomonas aeruginosa</i> gi|KP 16392| isolated from Sambhar salt lake in the southwest region of the city of Jaipur, India was tested for the first time for potential application in waste engine oil bioremediation and simultaneous biosurfactant production. In this study, the batch experiments were performed on culture grown in mineral salt medium supplemented with 5% (v/v) waste engine oil as the sole carbon source incubated for a week at pH 7.0, maintaining 35 °C and 150 rpm. The bacterial growth was monitored by the optical density and dry biomass content measurements. The biosurfactant production was affirmed with the reduction in surface tension of the culture medium from 72 ± 0.36 to 29.61 ± 0.14 mN/m. Of the total waste engine oil fed, 74.35 ± 0.037% was consumed and biodegraded to secondary metabolites. The biosurfactant yield was found to be approximately 1.02 g/L. The functional groups in the product, identified with the Fourier transf...

- by shailee gaur
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- Chemistry, Bioremediation, Rhamnolipid

In this paper, Pseudomonas aeruginosa MTCC7815, a biosurfactant producing strain was studied for its ability to utilize waste cooking oil (WCO) as a sole carbon source for the production of biosurfactant. Culture conditions were optimized based on surface tension reduction and biomass concentration. The obtained biosurfactant was characterized using 1H NMR, FTIR, LC–MS, and MALDI-TOF techniques. The chemical properties of the produced biosurfactant were estimated by assessing the critical micelle concentration (CMC), emulsification index (E24) and oil displacement test. The optimal culture conditions were found to be similar to the natural domestic sewage such as basic pH value of 10, temperature of 25 °C and a very high WCO concentration of 40 gL−1 (C/N ratio of 40/1). The biosurfactant yield was found to be significant as 11 ± 0.2 gL−1 upon utilizing about 90% of WCO within 5 days of incubation. The biosurfactant produced was found to be a mixture of mono- and di-rhamnolipid in nature and comprised excellent surface active properties i.e. an extremely low CMC of 8.8 ± 0.3 mgL−1, E24 of 62.5 ± 0.3% and surface tension reduction up to 26.2 ± 0.5 mNm−1. These results suggest the suitability of Pseudomonas aeruginosa for the biosurfactant production at commercial scale along with waste remediation in an economic way.

- by POULAMI DATTA
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- Microbiology, Chemistry, Biodegradation, Rhamnolipid
- by Pattanathu Rahman
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- Engineering, Technology, Biotechnology, Optimization techniques

- by Research in Molecular Medicine (RMM)
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- Antimicrobials, Surfactant, Rhamnolipid
- by Venkata N. Yarlagadda
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- Chemical Engineering, Marine Biology, Biomedical Engineering, Biofilms