Sophorolipids Research Articles

Rational high-throughput screening system for high sophorolipids production in Candida bombicola by co-utilizing glycerol and glucose capacity

BackgroundA rational and high-performance high-throughput screening system effectively improves the efficiency of strain screening.ResultsA rapid and efficient method was developed to detect carbon sources. And then by using glucose analog as screening pressure and two indexes for sophorolipids (SLs) production and glycerol consumption, a mutant of Candida bombicola L1.3 was successfully selected among 3000 mutants. It produces high SLs titer and co-utilizes glucose and glycerol simultaneously.ConclusionsCompared to the wild-type strain, L1.3 exhibited 15.06% higher SLs titer and 35.69% higher glycerol consumption capacity in a 5-L bioreactor. We believe that L1.3 can potentially be used for the efficient industrial production of SLs with simple downstream processing for separating SLs and glycerol.

Formulation and evaluation of wound healing activity of sophorolipid-sericin gel in wistar rats

Sericin is a useful by-product of silk processing and is resistant to oxidation and ultraviolet and can absorb and release moisture easily. Sericin has biological activities such as antibacterial, antioxidant, and tyrosinase inhibition. Sophorolipids are microbial extracellular glycolipids produced by resting cells of Candida bombicola. Sophorolipids show excellent skin compatibility and also have antibacterial property. In this study, we have developed a novel formulation consisting of sericin and sophorolipid with calcium alginate as a binding agent. Since both the ingredients are biocompatible and biodegradable, the formulation was tested for wound healing in Wistar rats. A commercial ointment povidone was used as control. The animal group, treated with sericin and sophorolipid cream, showed fast contraction, rapid closure, and healing when compared with control and commercial ointment. These observations were validated with histopathological studies where more fibroblast proliferation, angiogenesis, and keratinization were observed. This is a green, cost-effective formulation for fast wound healing.

Sophorolipid induced hydrothermal synthesis of Cu nanowires and its modulating effect on Cu nanostructures

Cu nanowires are important class of one dimensional metal nanowires with high electrical conductivity comparable to silver nanowires. Sophorolipid (SL), a well-known biosurfactant and glycolipid, plays significant role in the synthesis of nanomaterials as reducing and capping agent. Herein, we report the synthesis of Cu nanowires using sophorolipid by alkyl amine mediated hydrothermal synthesis and in this process, octadecylamine (ODA) used as alkyl amine. Cu nanowires of length ∼5−40μm and width ∼50−250 nm are produced at SL/ODA weight ratio of 0.13:1. Further structural investigations suggest that the morphology of these Cu nanostructures changes from nanowires to micron size rods and decahedron particles by modulating the weight ratio of SL and ODA.

Release of Pharmaceutical Peptides in an Aggregated State: Using Fibrillar Polymorphism to Modulate Release Levels

Traditional approaches to achieve sustained delivery of pharmaceutical peptides traditionally use co-excipients (e.g., microspheres and hydrogels). Here, we investigate the release of an amyloidogenic glucagon analogue (3474) from an aggregated state and the influence of surfactants on this process. The formulation of peptide 3474 in dodecyl maltoside (DDM), rhamnolipid (RL), and sophorolipid (SL) led to faster fibrillation. When the aggregates were subjected to multiple cycles of release by repeated resuspension in fresh buffer, the kinetics of the release of soluble peptide 3474 from different surfactant aggregates all followed a simple exponential decay fit, with half-lives of 5–18 min and relatively constant levels of release in each cycle. However, different amounts of peptide are released from different aggregates, ranging from 0.015 mg/mL (3475-buffer) up to 0.03 mg/mL (3474-DDM), with 3474-buffer and 3474-RL in between. In addition to higher release levels, 3474-DDM aggregates showed a different amyloid FTIR structure, compared to 3474-RL and 3474-SL aggregates and a faster rate of degradation by proteinase K. This demonstrates that the stability of organized peptide aggregates can be modulated to achieve differences in release of soluble peptides, thus coupling aggregate polymorphism to differential release profiles. We achieved aggregate polymorphism by the addition of different surfactants, but polymorphism may also be reached through other approaches, including different excipients as well as changes in pH and salinity, providing a versatile handle to control release profiles.

Enhanced short-chain fatty acids production from waste activated sludge by sophorolipid: Performance, mechanism, and implication

It was found in this study that the presence of sophorolipid (SL) enhanced the production of short-chain fatty acid (SCFA) from anaerobic fermentation of waste activated sludge (WAS). Experimental results showed that with an increase of SL addition from 0 to 0.1 g/g TSS, the maximal SCFA yield increased from 50.5 ± 4.9 to 246.2 ± 7.5 mg COD/g VSS. The presence of SL reduced the surface tension between hydrophobic organics and fermentation liquid, which thereby accelerated the disintegration of WAS and improved the biodegradability of the released organics. SL promoted the carbon/nitrogen ratio of the fermentation system, enhancing the conversion of proteins in WAS. Moreover, SL suppressed severely the activities of methanogens, probably due to the drop of pH caused by SL addition. Amplicon sequencing analyses revealed that SL increased the abundance of hydrolytic microbes such as Bacteroides sp. and Macellibacteroides sp., and SCFA producers (e.g., Acinetobacter sp.).

Rational high-throughput system for screening of high sophorolipids-producing strains of Candida bombicola

A rational high-throughput screening can significantly improve the efficiency of strain screening with high performance. In this study, based on the addition reaction of unsaturated fatty acids in the sophorolipids (SLs) and I2 molecules, a simple and rapid high-throughput detection method for SLs was established which demonstrated a correlation coefficient (R2) of 0.9106 with high-performance liquid chromatography (HPLC) method. Moreover, chlorpromazine, as a rational selecting pressure for enrichment of mutants with high cytochrome P450 enzyme activity, which was a key enzyme in the synthesis of SLs, was introduced into the high-throughput screening model. Consequently, with the aid of this effective screening system, a high-yielding mutant designated as Candida bombicola F6.5 was successfully screened out from 1500 single colonies, which presented improvements of 40.3% and 11.4% on SLs titer and yield, respectively, compared to the parent strain in a 1L bioreactor.

Antiangiogenic activity of sophorolipids extracted from refined bleached deodorized palm olein.

OBJECTIVES:Sophorolipids (SLs) are a group of surface-active glycolipids produced by a type of nonpathogenic yeast Candida bombicola in the presence of vegetable oil through fermentation technology. SLs have shown antitumor activity; however, the mechanism of action underlying the anticancer activity of SLs is poorly understood. This work evaluated the anticancer activity of SLs fermented from palm oil by exploring its antiangiogenic activity.MATERIALS AND METHODS:The SLs that were fermented and further characterized for their biochemical activities. Cytotoxicity study was performed to assess cytostatic properties. A series of in vitro and ex vivo angiogenesis assay was also carried out. The relative fold change in the expression of p53 mRNA by SLs was also studied.RESULTS:Altogether, the data show that SLs derived from palm oil fermentation process inhibited neovascularization in the ex vivo tissue segments and also the endothelial cell proliferation between 50% and 65% inhibition as a whole. The palm oil derived SLs also caused downregulation of the suppression level of vascular endothelial growth factor and also upregulate the p53 mRNA level. The analytical studies revealed the presence of high amount of phenolic compounds but with relatively weak antioxidant activity. The gas chromatography-mass spectrometry studies revealed abundant amount of palmitic and oleic acid, the latter an established antiangiogenic agent, and the former being proangiogenic.CONCLUSION:Therefore, it can be concluded from this study that SLs derived from fermented palm oil have potent antiangiogenic activity which may be attributed by its oleic acid component.

Investigation of fermentation conditions for Candida bombicola ACTT22214 from molasses and soybean oil for sophorolipid production

Sophorolipid (SL) is a biosurfactant belonging to the glycolipids group and was produced by harmless Candida bombicola ACTT22214 and has been widely used in many fields in our life. In order to search for appropriate condition for C. bombicola fermentation producing SL with high efficiency, this study focused on the investigation of the soy oil concentration, molasses concentration, fermentation time, pH and temperature. SL products were tested for antimicrobial activity, antioxidant, emulsifier, foaming ability. The highest content of SL was 43.27 ± 0.30 g/L under conditions of: soybean oil content 5%, molasses content 150 g/L, fermentation time 7 days, pH = 5, 28oC fermentation temperature. The antibacterial activity of SL was good: the highest resistance to Candida albicans (16.33 ± 1.15 mm), good resistance to Bacillus spizizenii (13.67 ± 0.58 mm), resistance to Staphylococcus aureus (12.67 ± 1.15 mm), relatively weak resistance to Pseudomonas aeruginosa (11.33 ± 0.58 mm) and Escherichia coli (9.67 ± 0.58 mm). The antioxidant capacity of SL was quite high with an IC50 value of 6.024 mg/mL. The emulsifying capacity of SL was equivalent to the emulsification of the tween 20 at a concentration of 5 - 10 mg/mL. SL had the ability to foam evenly from concentrations of 5 to 20 mg/mL but not higher than the corresponding concentrations of tween 20, SL was smooth, even, stable longer than tween 20

Impact of Select Sophorolipid Derivatives on Macrophage Polarization and Viability.

A major limitation of many biomaterials is the induction of a host response that challenges the integrity and overall efficacy of the implanted material. Emerging literature suggests that the resolution of inflammation is essential for proper healing and restoration of homeostasis. Macrophages are highly plastic immune cells that play a variety of critical roles throughout the duration of the host response. Specifically, the transition from a pro-inflammatory M1 phenotype to an anti-inflammatory/wound healing M2 macrophage phenotype is a central feature in the resolution of inflammation. The long-term goal of this work is to incorporate natural or modified sophorolipids (SLs), a class of glycolipids, as novel drug-loading or bioactive coating candidates to facilitate the resolution of biomaterial-induced inflammation. Toward this goal, the diacetylated lactonic SL (L) and seven SL-esters (modified to present methyl (M), ethyl (E), propyl (P), butyl (B), pentyl (Pent), hexyl (H), or octyl (O) groups) were compared with respect to macrophage viability and phenotype to identify promising SL-esters for biomaterial applications. An initial viability screen showed that certain SL-ester structures (L, Pent, and O) have relatively higher toxicity. Macrophage phenotypic assessments also revealed that most SL-esters suppressed the M1 profile in lipopolysaccharide-stimulated macrophages (M(LPS)). However, only two SL-ester candidates (E and B) were also capable of increasing the M2 profile in M(LPS), largely by enhancing the production of vascular endothelial growth factor A. Cumulatively, these results suggest that further investigation of SL-esters E and B for facilitating biomaterial-induced inflammation resolution is warranted.

Real-time dynamic analysis with low-field nuclear magnetic resonance of residual oil and sophorolipids concentrations in the fermentation process of Starmerella bombicola

The yeast Starmerella bombicola is known to produce sophorolipids (SLs) by fermentation method. In the fermentative production of SLs, at least three phases i.e. hydrophilic phase of glucose, ions and acidic-form SLs; hydrophobic phase of oil and lactone-form SLs; solid phase of cell biomass and SLs crystals are present in the broth. Therefore, a rapid and real-time detection of residual oil and SLs can provide valuable information in the regulation and optimization of the process to better produce SLs effectively. Looking into the importance, in this study, a rapid, accurate and precise method to quantify the concentrations of oil and SLs using low-field nuclear magnetic resonance (LF-NMR) was developed. Compared to the traditional weighing method, all the parameters for the evaluation of accuracy, precision and relative recovery presented better performances. Moreover, the proposed LF-NMR method could completely avoid using organic solvents that are commonly employed in the weighing method, besides shortening the pre-treatment and detection times from 24 h to just <20 min. Finally, LF-NMR method has been successfully used to monitor residual oil and SLs during the fermentation of Starmerella bombicola to obtain SLs and it has been observed that the production of SLs would be effectively improved by appropriately controlling the concentration of oil in terms of titer, productivity and yield.

Removal of Cadmium and Lead from Contaminated Soils Using Sophorolipids from Fermentation Culture of Starmerella bombicola CGMCC 1576 Fermentation.

Soil contaminated with Cd and Pb has caused sharp decrease of cultivatable soil and has been attracting increasing attention. Biosurfactants are efficient in solving the problem. However, little information is available about the influence of sophorolipids (SLs) on the remediation of Cd- or Pb-contaminated soil. The sophorolipids produced by Starmerella bombicola CGMCC 1576 were used to study the effects of Cd and Pb removal in batch soil washing from artificially contaminated soil. The removal efficiency of crude total SLs was better than both distilled water and synthetic surfactants. Furthermore, 83.6% of Cd and 44.8% of Pb were removed by 8% crude acidic SLs. Acidic SLs with high water solubility were more effective than lactonic SLs in enhancing remediation of heavy metal-contaminated soils. The complexation of Cd with the free carboxyl group of the acidic SLs was observed by Fourier-transform infrared spectroscopy study, and this complexation was effective in heavy metal removal from the soil. The fermentation broth of S. bombicola, without further preparation, removed 95% of Cd and 52% of Pb. These results suggested that SLs produced by S. bombicola could function as potential bioremediation agents for heavy metal-contaminated soil.

Composite Biopolymer-Based Wafer Dressings Loaded with Microbial Biosurfactants for Potential Application in Chronic Wounds.

In this study two bioactive polysaccharide polymers kappa-carrageenan (CARR) and sodium alginate (SA) incorporated with microbial biosurfactants (BSs) were formulated as medicated wafer dressings for potential application in chronic wounds. Wafers were loaded with BSs at concentrations of 0.1% and 0.2% rhamnolipids (RL) and 0.1% and 5% sophorolipids (SL) and were functionally characterized using scanning electron microscopy (SEM), texture analysis (mechanical strength and in vitro wound adhesion), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray diffraction (XRD) and exudate handling properties (pore analysis, swelling index, water absorption (Aw), equilibrium water content (EWC), evaporative water loss (EWL) and water vapor transmission rate (WVTR). The wafers were tactile and ductile in appearance with a hardness range of 2.7–4.1 N and can withstand normal stresses but are also flexible to prevent damage to newly formed skin tissues. Wafers were porous (SEM) with pore sizes ranging from 78.8 to 141 µm, and BSs were not visible on the wafer surface or pore walls. The BSs enhanced the porosity of the wafers with values above 98%, while the Aw and EWC ranged from 2699–3569% and 96.58–98.00%, respectively. The EWL ranged from 85 to 86% after 24 h while the WVTR ranged from 2702–3080 g/m2 day−1. The compatibility of BSs within the CARR-SA matrix was confirmed by seven characteristic functional groups which were consistently transmitted in the ATR-FTIR spectra. These novel medicated dressing prototypes can potentially help to achieve more rapid wound healing.

An eco-friendly method for heavy metal removal from mine tailings.

One of the serious environmental problems that society is facing today is mine tailings. These byproducts of the process of extraction of valuable elements from ores are a source of pollution and a threat to the environment. For example, mine tailings from past mining activities at Giant Mines, Yellowknife, are deposited in chambers, stopes, and tailing ponds close to the shores of The Great Slave Lake. One of the environmentally friendly approaches for removing heavy metals from these contaminated tailing is by using biosurfactants during the process of soil washing. The objective of this present study is to investigate the effect of sophorolipid (SL) concentration, the volume of washing solution per gram of medium, pH, and temperature on the efficiency of sophorolipids in removing heavy metals from mine tailings. It was found that the efficiency of the sophorolipids depends on its concentration, and is greatly affected by changes in pH, and temperature. The results of this experiment show that increasing the temperature from 15 to 23°C, while using sophorolipids, resulted in an increase in the removal of iron, copper, and arsenic from the mine tailing specimen, from 0.25, 2.1, and 8.6 to 0.4, 3.3, and 11.7%. At the same time, increasing the temperature of deionized water (DIW) from 15 to 23°C led to an increase in the removal of iron, copper, and arsenic from 0.03, 0.9, and 1.8 to 0.04, 1.1, and 2.1%, respectively. By increasing temperature from 23 to 35°C, when using sophorolipids, 22% reduction in the removal of arsenic was observed. At the same time while using DI water as the washing solution, increasing temperature from 23 to 35°C resulted in 6.2% increase in arsenic removal. The results from this present study indicate that sophorolipids are promising agents for replacing synthetic surfactants in the removal of arsenic and other heavy metals from soil and mine tailings.

From lab to market: An integrated bioprocess design approach for new-to-nature biosurfactants produced by Starmerella bombicola.

Glycolipid microbial biosurfactants, such as sophorolipids (SLs), generate high industrial interest as 100% biobased alternatives for traditional surfactants. A well-known success story is the efficient SL producer Starmerella bombicola, which reaches titers well above 200 g/L. Recent engineering attempts have enabled the production of completely new types of molecules by S. bombicola, e.g. the bolaform SLs. Scale-up of bolaform SL production was performed at 150 L scale. The purified product was evaluated in detergent applications, as classic SLs are mostly applied in eco-friendly detergents. In this paper, we show that they can be used as green and non-irritant surfactants in for example (automatic) dishwashing applications. However, due to the presence of an ester function in the biosurfactant molecule a limited chemical stability at higher pH values (>6.5) was noticed, (therefore called 'non-symmetrical' (nsBola)) which, is a major drawback that will most likely inhibit market introduction. An integrated bioprocess design (IBPD) strategy was thus applied to resolve this issue. The strategy was to replace the fed fatty acids with fatty alcohols, to generate so-called "symmetrical bolaform (sBola) sophorosides (SSs)," containing two instead of one glycosidic bond. Next to a change in feeding strategy, the blocking of the fatty alcohols from metabolizing/oxidizing through the suggested ω-oxidation pathway was necessary. For the latter, two putative fatty alcohol oxidase genes (fao1 and fao2) were identified in the S. bombicola genome and deleted in the bolaform SL producing strain (ΔatΔsble). Shake flask experiments for these new strains (ΔatΔsbleΔfao1 and ΔatΔsbleΔfao2) were performed to evaluate if the fed fatty alcohols were directly implemented into the SL biosynthesis pathway. Indeed, sBola sophorosides (SSs) production up to 20 g/L was observed for the ΔatΔsbleΔfao1 strain. Unexpectedly, the ΔatΔsbleΔfao2 strain only produced minor amounts of sBola sophorosides (SSs), and mainly nsBola SLs (alike the parental ΔatΔsble strain). The sBola sophorosides (SSs) were purified and their symmetrical structure was confirmed by NMR. They were found to be significantly more stable at higher pH, opening up the application potential of the biosurfactant by enhancing its stability properties.

Efficient Production of Acid-Form Sophorolipids from Waste Glycerol and Fatty Acid Methyl Esters by &lt;i&gt;Candida floricola&lt;/i&gt;

We discovered that Candida floricola ZM1502 is capable of selectively producing the promising hydrophilic biosurfactants, acid-form sophorolipids (SLs), from glycerol. However, productivity was very low (approximately 3.5 g L-1) under the initial culture conditions. Here, we describe the design of culture medium for abundant production of acid-form SLs by C. floricola ZM1502 using waste glycerol and hydrophobic substrates in order to develop a method for SL production and disposal of waste glycerol produced by oleo-chemical industries. Urea provided the best nitrogen source for acid-form SL production from glycerol among four nitrogen sources tested [urea, NaNO3, NH4NO3, and (NH4)2SO4]. Among carbon sources we compared, hydrophobic substrates (soybean oil and oleic acid) led to productivities of approximately 20 g L-1, indicating that hydrophobic substrates provided fatty acid moieties for SL production. Addition of olive oil and oleic acid to waste glycerol enhanced acid-form SL production to 42.1 ± 0.9 and 37.5 ± 3.4 g L-1, respectively. To develop a potential industrial process, we explored other suitable hydrophobic substrates for SL production, which were obtained on site from oleo-chemical industries. Alkyl C18 esters (Pastell M-182), along with waste glycerol, increased acid-form SL production to 48.0 ± 3.4 g L-1 over a 7-d period. Furthermore, we demonstrated abundant production of acidic SLs at the mini-jar fermenter scale, obtaining 169 g L-1 over 180 h using a fed-batch cultivation technique. Efficient acid-form SL production by C. floricola could have a great impact on the development of bio-industrial processes using waste glycerol as a substrate.

In vivo topical delivery of ethosomal formulation composed of Orthosiphon stamineus extract complexed with sophorolipid against melanoma

Event Abstract Back to Event In vivo topical delivery of ethosomal formulation composed of Orthosiphon stamineus extract complexed with sophorolipid against melanoma Mansoureh Nazari Vishkaei1, Mohamed Khadeer Ahamed Basheer2 and Amin Malik Shah Abdul Majid3* 1 School of Pharmaceutical Sciences, University of Science Malaysia, Malaysia 2 Emanbiodiscoveries.sdn.bhd., Malaysia 3 University of Science, Malaysia, Malaysia Background Melanoma is one of the most aggressive types of skin cancers. Anti-angiogenic compounds can suppress melanoma cells. Orthosiphon stamineus (O.S) is a well-known herb with anticancer and anti-angiogenic effects. The health benefits of O.S extract is mainly due to its high antioxidant activity that can be attributed to rosmarinic acid (RA). However, RA has a limited ability to penetrate through the skin because of its hydrophilicity via topical application. The aim of this study is therefore to improve the penetrability of O.S extract through skin by sophorolipid (SL) nanovesicles, namely ethosome in mice. Methods Ethosome was made using thin film hydration method with sophorolipid as the surfactant. The ethosomal formulation of O.S (O.S-SL) was prepared at different concentrations and were physico-chemically characterized. Anti-angiogenic studies were then conducted. Anti-melanoma study was performed in albino mice using melanoma cell line (B16F10). Results The optimized vesicle was 387nm in size with -35.6mV potential and exhibited 10 times better permeation ability when compared to the hydroethanolic solution of O.S extract. O.S-SL revealed 100% anti-angiogenic effect ex vivo and 95.8% anti-melanoma effect in vivo. Conclusion The results of this study demonstrated that O.S-SL can be absorbed efficiently via topical application to the deeper layers of the skin. The formulation has shown promising anti-angiogenic and anti-melanoma effects after topical applications. Acknowledgements The authors would like to express their gratitude to Universiti Sains Malaysia, EMAN Biodiscoveries Sdn. Bhd. and NatureCeuticals Sdn. Bhd. for providing research facilities. Keywords: Orthosiphon stamineus, Ethosome, Sophorolipid, Melanoma, Topical Conference: International Conference on Drug Discovery and Translational Medicine 2018 (ICDDTM '18) “Seizing Opportunities and Addressing Challenges of Precision Medicine”, Putrajaya, Malaysia, 3 Dec - 5 Feb, 2019. Presentation Type: Oral Presentation Topic: Cancer Citation: Nazari Vishkaei M, Khadeer Ahamed Basheer M and Malik Shah Abdul Majid A (2019). In vivo topical delivery of ethosomal formulation composed of Orthosiphon stamineus extract complexed with sophorolipid against melanoma. Front. Pharmacol. Conference Abstract: International Conference on Drug Discovery and Translational Medicine 2018 (ICDDTM '18) “Seizing Opportunities and Addressing Challenges of Precision Medicine”. doi: 10.3389/conf.fphar.2018.63.00034 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 21 Oct 2018; Published Online: 17 Jan 2019. * Correspondence: Prof. Amin Malik Shah Abdul Majid, University of Science, Malaysia, George Town, Penang, 11800, Malaysia, aminmalikshah@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Mansoureh Nazari Vishkaei Mohamed Khadeer Ahamed Basheer Amin Malik Shah Abdul Majid Google Mansoureh Nazari Vishkaei Mohamed Khadeer Ahamed Basheer Amin Malik Shah Abdul Majid Google Scholar Mansoureh Nazari Vishkaei Mohamed Khadeer Ahamed Basheer Amin Malik Shah Abdul Majid PubMed Mansoureh Nazari Vishkaei Mohamed Khadeer Ahamed Basheer Amin Malik Shah Abdul Majid Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Optimization of washing conditions with biogenic mobilizing agents for marine fuel-contaminated beach sands

Washing is a rapid and effective treatment to remediate contaminated sands impacted by oil spills, although synthetic additives used to increase extraction efficiency may cause additional pollution issues due to their intrinsic toxicity and very often low biodegradability. In this study, different biogenic mobilizing agents (soybean lecithins, cyclodextrins, cholic acids, plant-derived cleaners, rhamnolipids and sophorolipids) were tested in the washing of beach sands artificially contaminated with the Intermediate Fuel Oil IFO-180. Among these, a de-oiled soybean lecithin (SL-1), hydroxypropyl-β-cyclodextrins (HPB-CD) and sophorolipids (SR) achieved hydrocarbon removals close to those attained with the synthetic surfactant Triton™ X-100 (TX) in preliminary washing tests carried out at constant mixing rate, water/sand ratio and IFO-180 contamination level using agents concentrations close to their critical micelle concentration (0.1% and 1% w/v for microbial and non-microbial agents, respectively). The effects of agent concentration, water/sand ratio, mixing rate and IFO-180 contamination on hydrocarbons removal were modelled using face-centred central composite design and ANOVA. Optimal washing parameters for sand contamination levels in the range 0.5–20 g/kg were identified with response surface methodology. While HPB-CD and SR performed equally to TX only at low sand contaminations, SL-1 attained hydrocarbon removal higher or equal to that of TX at any IFO-180 contamination and at lower application rates. SL-1 also outperformed TX when minimizing the water/sand ratio, i.e., the volume of water used. Considering its lower toxicity, higher biodegradability and higher hydrocarbon removal efficiencies, SL-1 is an effective and environmentally sustainable alternative to synthetic surfactants in washing treatments for marine fuel-contaminated sands.

Reductionin Listeria monocytogenes, Salmonella enterica and Escherichia coli O157:H7 in vitro and on tomato by sophorolipid and sanitiser as affected by temperature and storage time

SummaryIncreased consumption of produce by consumers has been attributed to perceived health benefits of postharvest produce. Pathogen control is crucial because periodic occurrences and contamination of tomato and leafy greens have exacerbated food safety risks for consumers. We investigated the effects of temperatures (5 and 25 °C), storage time (30 min and 24 h) for inactivation of Listeria monocytogenes, Salmonella enterica and Escherichia coli O157:H7 by sophorolipid (SL‐p) produced fermentatively using palmitic acid as a co‐substrate at different concentrations in vitro. Reduction in pathogenic bacteria on grape tomato by SL‐p, sanitiser (Lovit) and combinations of SL‐p and sanitiser was determined. Temperature and storage time significantly (P &lt; 0.05) affected pathogen inactivations by SL‐p as pathogen reductions were greater at 25 °C and 24 h than at 5 °C and 30 min of storage. L. monocytogenes was the most sensitive to SL‐p treatment as reductions of 5 log relative to untreated controls were attained at 0.12% of SL‐p. Significant reductions in S. enterica (1.91–3.85 logs) and E. coli O157:H7 (0.87–4.09 logs) were recorded at 2–5% of SL‐p. Lower populations of Salmonella and E. coli O157:H7 were inactivated than L. monocytogenes. On grape tomato, pathogen populations inactivated increased at higher SL‐p levels at 25 °C. Sanitiser and sanitiser + SL‐p reduced bacterial populations on tomato by 5.29–5.76 logs and 0.71–3.3.66 logs, respectively. These results imply the interactions of temperature, storage time and SL‐p significantly (P &lt; 0.05) affected pathogen strain reductions. The combination of SL‐p with sanitiser led to synergistic effect on E. coli O157:H7, but not L. monocytogenes and S. enterica.

Anti-biofilm activity of a sophorolipid-amphotericin B niosomal formulation against Candida albicans

Sophorolipids (SLs) have gained interest in the pharmaceutical industries due to their anti-microbial, anti-adhesive and anti-biofilm properties. In the present study, the production of SL was increased by using low-cost media components. The potential of a SL-based niosomal formulation of amphotericin B (AmB) was determined against biofilm of the opportunistic fungal pathogen Candida albicans. In-house prepared SL-AmB niosomes were characterized by different microscopic techniques. The mean entrapment efficiency of AmB within SL-AmB niosome was 63.20% ± 3.86. The cytotoxicity of SL-AmB on mature C. albicans biofilm was compared with an expensive, marketed drug, viz. phosome (a liposomal formulation of AmB). Fewer hyphae were observed in C. albicans biofilm treated with SL-AmB niosome whereas more budding cells were found in phosome treated biofilm. The present study has established the affordable production of SL and the suitability of this approach for delivery of poorly soluble drugs such as AmB against candidiasis infections.

Progress of Biosynthesis of Sophorolipids and Its Derivatives Production in Starmerella bombicola

Progress of Biosynthesis of Sophorolipids and Its Derivatives Production in Starmerella bombicola