Search Results (15)

Significant wastes such as bagasse, molasses, and vinasses are produced during sugarcane processing. Due to their high sugar content, these wastes are commonly used as low-cost substrates for biofuel production. However, these substrates are also suitable for the microbial synthesis of high-value biochemicals like biosurfactants. Sporisorium scitamineum, a smut fungus capable of growing on sugarcane residues and producing mannosylerythritol lipids (MELs) and cellobiose lipids (CBLs), was identified as a promising candidate for valorizing sugarcane wastes. This study investigated MEL and CBL co-production from pure sugars and sugarcane molasses using an S. scitamineum strain isolated from sugarcane residues originating from KwaZulu-Natal, South Africa. Among the sugars tested, sucrose supported the highest glycolipid production, yielding 0.24 g/L MELs and 2.73 g/L CBLs. Lower titers were achieved with fructose, and no production occurred with glucose. Sugarcane molasses also proved to be an effective substrate, yielding 1.46 g/L CBLs—the highest reported titer from an industrial waste to date. However, all titers remained far below those of other glycolipids, which consistently exceed 50 g/L. Future efforts should focus on enhancing CBL production through process optimization or genetic engineering. Full article

Fermentations are complex and often unpredictable processes. However, fermentation-based bioprocesses generate large volumes of data that are currently underexplored. These data can be used to develop data-driven models, such as machine learning (ML) models, to improve process predictability. Among various fermentation products, biosurfactants have emerged as promising candidates for several industrial applications. Nevertheless, the large-scale production of biosurfactants is not yet cost-effective. This study aims to develop forecasting methods for the concentration of mannosylerythritol lipids (MELs), a type of biosurfactant, produced in Moesziomyces spp. cultivation. Three ML models, neural networks (NNs), support vector machines (SVMs), and random forests (RFs), were used. An NN provided predictions with a mean squared error (MSE) of 0.69 for day 4 and 1.63 for day 7 and a mean absolute error (MAE) of 0.58 g/L and 1.1 g/L, respectively. These results indicate that the model’s predictions are sufficiently accurate for practical use, with the MAE showing only minor deviations from the actual concentrations. Both results are promising, as they demonstrate the possibility of obtaining reliable predictions of the MEL production on days 4 and 7 of fermentation. This, in turn, could help reduce process-related costs, enhancing its economic viability. Full article

Mannosylerythritol lipids (MELs), one of the most promising biosurfactants (BS), are glycolipids produced by yeasts or fungi, which have great environmental performance and high compatibility with the human body. MELs, besides working as typical surfactants, can form diverse structures when at or above the critical aggregation concentration (CAC), reduce the surface tension of water and other solutions, and be stable over a wide range of conditions. Among others, MELs present antimicrobial, antitumor, antioxidant and anti-inflammatory activities and skin and hair repair capacity, which opens possibilities for their use in applications from cosmetics and pharmaceutics to bioremediation and agriculture. However, their market share is still low when compared to other glycolipids, due to their less developed production process and higher production cost. This review gathers information on the potential applications of MELs mentioned in the literature since 1993. Furthermore, it also explores the current strategies being developed to enhance the market presence of MELs, in parallel with the ones developed for rhamnolipids and sophorolipids. Full article

Mannosylerythritol lipids (MELs) are a class of glycolipids that have been receiving increasing attention in recent years due to their diverse biological activities. MELs are produced by certain fungi and display a range of bioactivities, making them attractive candidates for various applications in medicine, agriculture, and biotechnology. Despite their remarkable qualities, industrial-scale production of MELs remains a challenge for fungal strains. Excellent fungal strains and fermentation processes are essential for the efficient production of MELs, so efforts have been made to improve the fermentation yield by screening high-yielding strains, optimizing fermentation conditions, and improving product purification processes. The availability of the genome sequence is pivotal for elucidating the genetic basis of fungal MEL biosynthesis. This review aims to shed light on the applications of MELs and provide insights into the genetic basis for efficient MEL production. Additionally, this review offers new perspectives on optimizing MEL production, contributing to the advancement of sustainable biosurfactant technologies. Full article

The application of pesticides in agriculture leads to improved crop quality and promotes high productivity. However, the uninterrupted use of these chemicals is directly related to environmental impacts, affecting biodiversity and the health of ecosystems and humans. In this sense, mannosylerythritol lipids (MELs) are a promising alternative, as they are biosurfactants with antimicrobial, amphiphilic characteristics, and low toxicity. Thus, in search of a partial reduction in the use of chemical pesticides in agriculture, this work aimed to evaluate the biostimulant effect of one of the homologs of MELs–MEL-B on the germination of Monica lettuce seeds (Lactuca sativa L.) and the influence on plant growth and root development. The seeds germinated in different concentrations of MEL-B. The incidence of germinated seeds, the germination index, and the average germination time were evaluated. MEL-B at 158 mg/L stimulated seed germination, growth, and seedling development parameters by 65%, while concentrations of 316 and 632 mg/L did not exceed 45% for these parameters. It was observed that MEL-B at 158 mg/L biostimulated the appearance of lateral roots and promoted only 7% of root stress, a difference of 47% for roots grown with MEL-B at 632 mg/L. Furthermore, MEL-B at 158 mg/L was the highest concentration at which there was no phytotoxic effect of MEL-B on seeds. The increase in enzymatic activity corroborates the phytotoxic effect and seed stress at concentrations of 316 and 632 mg/L, showing results of 47% and 54% of stressed roots. In an unprecedented way, this study proved that MEL-B has a biostimulant and phytotoxic effect related to its concentration. Full article

Glycolipid biosurfactants are the most prominent group of microbial biosurfactants, comprising rhamnolipids, sophorolipids and mannosylerythritol lipids (MELs). Usually, large amounts of hydrophobic substrates (e.g., vegetable oils) are used to achieve high titers (~200 g/L) of a crude product of low purity at values limited to 50–60%, contaminated with unconsumed triacylglycerol and residual free fatty acids and monoacylglycerides. The methods reported for the removal of these contaminants use a mixture of organic solvents, compromising solvent recyclability and increasing final process costs. This study reports, for the first time, an innovative downstream method for MELs, in which 90% of the triacylglycerols are separated from the crude MEL mixture in a first stage and the other lipid derivatives (free fatty acids, mono- and diacylglycerols) are removed by organic solvent nanofiltration (OSN). Three commercially available membranes (GMT-oNF-2, PuraMEm-600 and DuramMem-500) and several homemade membranes, casted from 22, 24 or 26% (w/v) polybenzimidazole (PBI) solutions, were assessed for crude MELs purification by diafiltration. A final purity of 87–90% in the MELs was obtained by filtering two diavolumes of methanol or ethyl acetate solutions through a PBI 26% membrane, resulting in MELs losses of 14.7 ± 6.1% and 15.3 ± 2.2%, respectively. Higher biosurfactant purities can be archived using the PBI 26% membrane at higher DV, but at the cost of higher product losses. Namely, in MeOH, the use of 6 DV leads to losses of 32% for MELs and 18% for sophorolipids. To obtain MELs at reagent grade with purities equal or higher than 97%, a two-sequential cascade filtration approach was implemented using the commercial membrane, GMT-oNF. In such a process, MELs with 98% purity was obtained at the cost of 11.6% MELs losses. Finally, decoloration, important in some applications, was successfully assessed using activated carbon. Overall, this study reports a unique solution for microbial biosurfactants production with minimal product losses, enabling solvent recycling and potentially reducing costs. Full article

Mannosylerythritol lipids (MELs) are biosurfactants with excellent biochemical properties and a wide range of potential applications. However, most of the studies focusing on MELs high titre production have been relying in the use of vegetable oils with impact on the sustainability and process economy. Herein, we report for the first time MELs production using oils produced from microalgae. The bio-oil was extracted from Neochloris oleoabundans and evaluated for their use as sole carbon source or in a co-substrate strategy, using as an additional carbon source D-glucose, on Moesziomyces spp. cultures to support cell growth and induce the production of MELs. Both Moesziomyces antarcticus and M. aphidis were able to grow and produce MELs using algae-derived bio-oils as a carbon source. Using a medium containing as carbon sources 40 g/L of D-glucose and 20 g/L of bio-oils, Moesziomyces antarcticus and M. aphidis produced 12.47 ± 0.28 and 5.72 ± 2.32 g/L of MELs, respectively. Interestingly, there are no significant differences in productivity when using oils from microalgae or vegetable oils as carbon sources. The MELs productivities achieved were 1.78 ± 0.04 and 1.99 ± 0.12 g/L/day, respectively, for M. antarcticus fed with algae-derived or vegetable oils. These results open new perspectives for the production of MELs in systems combining different microorganisms. Full article

Mannosylerythritol lipids (MELs) are a group of biosurfactants with a wide range of potential applications, due to their excellent tensioactive properties, biocompatibility, and biodegradability. One of the envisioned uses for MELs is in bioremediation in marine and terrestrial environments. However, knowledge regarding their ecotoxicity is limited. The current costs of production for this biosurfactant are too high to make it competitive in the surfactant market. In an effort to facilitate the use of MELs for marine bioremediation purposes, their production using sea water in medium formulation was explored. Cells were exposed to different levels of NaCl during fermentation, and the effects of increased salinity on the cells and their performance was monitored. In addition, cells were briefly exposed to an osmotic shock, by introducing pure NaCl into the broth, to measure their physiological response. Although the overall effect of NaCl in the medium was negative, cells produced more lipases in these stress conditions. Furthermore, the changes triggered by the osmotic shock caused changes in the cell surface and affected their hydrophobicity, reducing the levels of MELs adsorbed to the cells, which in turn led to an increase in formation of MEL-rich beads. Marine-level salinity (3.5%) was found to be sufficient to enable production of MELs in unsterile conditions and inhibited an introduced bacterial contaminant. Finally, the toxicity levels of MELs to a model marine organism and plant model were lower than other biosurfactants and that of a commercial chemical dispersant used for bioremediation. Full article

Protein-surfactant interactions have a significant influence on food functionality, which has attracted increasing attention. Herein, the effect of glycolipid mannosylerythritol lipid-A (MEL-A) on the heat-induced soy glycinin (11S) aggregates was investigated by measuring the structure, binding properties, interfacial behaviors, and emulsification characteristics of the aggregates. The results showed that MEL-A led to a decrease in the surface tension, viscoelasticity, and foaming ability of the 11S aggregates. In addition, MEL-A with a concentration above critical micelle concentration (CMC) reduced the random aggregation of 11S protein after heat treatment, thus facilitating the formation of self-assembling core-shell particles composed of a core of 11S aggregates covered by MEL-A shells. Infrared spectroscopy, circular dichroism spectroscopy, fluorescence spectroscopy, and isothermal titration calorimetry also confirmed that the interaction forces between MEL-A and 11S were driven by hydrophobic interactions between the exposed hydrophobic groups of the protein and the fatty acid chains or acetyl groups of MEL-A, as well as the hydrogen bonding between mannosyl-D-erythritol groups of MEL-A and amino acids of 11S. The findings of this study indicated that such molecular interactions are responsible for the change in surface behavior and the enhancement of foaming stability and emulsifying property of 11S aggregates upon heat treatment. Full article

Research on biosurfactants (BS) is consistently increasing in the past years, driven from their beneficial attributes over chemical surfactants. Lactobacilli (LAB) and yeast BS producers could prevail over the pathogenic strains, owing to their GRAS status, to broaden end-applications toward the food and pharmaceutical industries. However, the increased cost of production confers a bottleneck for the industrial manufacture. Hence, the exploitation of agro-industrial waste and by-products as fermentation supplements is currently on the spotlight. This study elaborates on the efficient production of lactobacilli and Moesziomyces BS via cheese whey (CW) bioprocessing. Subsequently, the obtained BS were individually assessed in fermented milk production using as starter culture the initial LAB strain used for BS synthesis. Physicochemical and microbiological assessment was performed during storage. Results indicated that LAB-BS addition increased the lactobacilli concentration, whereby mannosylerythritol lipids (MEL) inclusion showed a positive effect on syneresis. Aiming to develop a closed-loop process, for the first time, LAB cells after BS extraction were sequentially applied for sour milk production, demonstrating the ability for cell re-utilization. This study introduces a holistic and circular configuration that consolidates CW valorization for BS production, that are re-introduced in the food supply, to complement the resilience of the dairy industry. Full article

Mannosylerythritol lipids-A (MEL-A) is a novel biosurfactant with multiple biological effects. The synergistic antibacterial activity and mechanism of MEL-A and lactic acid (LA) against Listeria monocytogenes were investigated. The synergistic effect resulted in a significant increase in the antibacterial rate compared to LA treatment alone. Genome-wide transcriptomic analysis was applied to deeply investigate the synergistic antibacterial mechanism. Gene Ontology (GO) enrichment analysis showed that the synergy between MEL-A and LA affected many potential cellular responses, including the sugar phosphotransferase system, carbohydrate transport, and ribosomes. KEGG enrichment analysis showed that the PTS system and ribosome-related pathways were significantly enriched. In addition, synergistic treatment affected locomotion and membrane-related cellular responses in GO enrichment analysis and carbohydrate metabolism and amino acid metabolism pathways in KEGG enrichment analysis compared to LA treatment alone. The accuracy of the transcriptome analysis results was verified by qPCR (R² = 0.9903). This study will provide new insights for the prevention and control of L. monocytogenes. Full article

Mannosylerythritol lipids (MELs) may prevent skin barrier damage, although their protective mechanisms and active monomeric constituents remain unclear. Here, three MELs were extracted from Candida antarctica cultures containing fermented olive oil then purified using silica gel-based column chromatography and semipreparative HPLC. All three compounds (MEL-A, MEL-B, MEL-C) were well separated and stable, and reliable materials were used for NMR and HRESIMS chemical structure determinations and for assessing MELs’ protective effects against skin damage. Notably, MEL-B and MEL-C effectively protected HaCaT cells from UVB-induced damage by upregulating the contents of filaggrin (FLG) and transglutaminase-1 (TGM1), as determined via ELISA. Moreover, MEL-B treatment (20 μg/mL) of UVB-irradiated HaCaT cells led to the upregulation of both the expression of mRNA genes and the key proteins FLG, LOR, and TGM1, which are known to be decreased in damaged skin cells. Additionally, histopathological analysis results revealed a markedly reduced intracellular vacuolation and cell damage, reflecting improved skin function after MEL-B treatment. Furthermore, immunofluorescence results revealed that MEL-B protected EpiKutis^® three-dimensional cultured human skin cells from sodium dodecyl sulfate-induced damage by up-regulating FLG, LOR, and TGM1 expression. Accordingly, MELs’ protection against skin barrier damage depended on MEL-B monomeric constituent activities, thus highlighting their promise as beneficial ingredients for use in skin-care products. Full article

Mannosylerythritol lipids-A (MEL-A) is a novel biosurfactant with excellent surface activity and potential biomedical applications. In this study, we explored the antibacterial activity and the underlying mechanisms of MEL-A against the important food-borne pathogen Listeria monocytogenes. The bacterial growth and survival assays revealed a remarkable antibacterial activity of MEL-A. Since MEL-A is a biosurfactant, we examined the cell membrane integrity and morphological changes of MEL-A-treated bacteria by biochemical assays and flow cytometry analysis and electron microscopes. The results showed obvious damaging effects of MEL-A on the cell membrane and morphology. To further explore the antibacterial mechanism of MEL-A, a transcriptome analysis was performed, which identified 528 differentially expressed genes (DEGs). Gene ontology (GO) analysis revealed that the gene categories of membrane, localization and transport were enriched among the DEGs, and the analysis of the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways demonstrated significant changes in the maltodextrin ABC transporter system and stress response system. Furthermore, the growth of L. monocytogenes could also be significantly inhibited by MEL-A in milk, a model of a real food system, suggesting that MEL-A could be potentially applied as an natural antimicrobial agent to control food-borne pathogens in the food industry. Full article

We confirmed that mannosylerythritol lipid B (MEL-B), a biosurfactant, enhances the skin permeability of the model water-soluble compound calcein. MEL-B liposomes were prepared by the thin-layer evaporation technique, and then applied to the skin. Although we attempted to adjust the size by extrusion, we could not control the particle diameter of the liposomes. However, the MEL-B liposome particle diameter remained the same over the 7-day study period. We observed an endothermic peak, with 74.7 °C as the transition temperature by differential scanning calorimetry. We also performed a fusion experiment with a fluorescence resonance energy transfer. A high amount of fusion of intercellular lipid liposomes and MEL-B liposomes occurred in a short period of time. After applying the MEL-B liposomes containing calcein to the skin, we measured the degree of calcein permeation and the amount of calcein within the skin. The resulting values were higher than those of an aqueous solution. The results obtained using a confocal laser scanning microscope suggested that calcein had been delivered deeply into the skin. Using the attenuation of total reflectance Fourier-transform infrared spectrometry, we observed that the OH stretching vibration had shifted to a higher wavenumber; however, this did not affect the CH stretching vibration. The measurement of transepidermal water loss after four days of continuous application of 1% MEL-B to animals revealed no changes. Our results suggest that MEL-B increases the skin permeability of compounds (calcein) that are difficult to deliver transdermally by changing the OH stretching vibration, which shifts to a higher wavenumber. Full article

As a novel natural compound delivery system, liposomes are capable of incorporating lipophilic bioactive compounds with enhanced compound solubility, stability and bioavailability, and have been successfully translated into real-time clinical applications. To construct the soy phosphatidylcholine (SPC)–cholesterol (Chol) liposome system, the optimal formulation was investigated as 3:1 of SPC to Chol, 10% mannosylerythritol lipid-A (MEL-A) and 1% betulinic acid. Results show that liposomes with or without betulinic acid or MEL-A are able to inhibit the proliferation of HepG2 cells with a dose-effect relation remarkably. In addition, the modification of MEL-A in liposomes can significantly promote cell apoptosis and strengthen the destruction of mitochondrial membrane potential in HepG2 cells. Liposomes containing MEL-A and betulinic acid have exhibited excellent anticancer activity, which provide factual basis for the development of MEL-A in the anti-cancer applications. These results provide a design thought to develop delivery liposome systems carrying betulinic acid with enhanced functional and pharmaceutical attributes. Full article