Sophie Roelants

Sophie Roelants
Ghent University | UGhent · Faculty of Bioscience Engineering

PhD

About

77
Publications
11,684
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Introduction
Sophie Roelants currently works at the Faculty of Bioscience Engineering, Ghent University in the department Biotechnology and research group InBio.be. She also works at the Bio Base Europe Pilot Plant, which is a service provider and research institute focussing on process development and scale up of bioprocesses up to 50 m³ (biocatalysis) and 15 m³ (fermentation) scale. Her research focusses on the development of new Starmerella bombicola yeast strains producing new types of biosurfactants and developping processes for the production of these new compounds, while also exploring their application potential.
Additional affiliations
January 2009 - present
Ghent University
Position
  • PhD

Publications

Publications (77)
Article
Biological amphiphiles derived from natural resources are presently being investigated in the hope that they will someday replace current synthetic surfactants, which are known pollutants of soils and water resources. Sophorolipids constitute one of the main classes of glycosylated biosurfactants that have attracted interest because they are synthe...
Article
Chameleons are stunning reptiles which change colour according to the surrounding environment. In astrophysics, chameleons are particles whose mass varies in the surrounding matter. Here, we show the chameleonic self-assembly behavior of a low molecular weight (LMW) amphiphile, a broad class of molecules widely studied for several decades. Their ab...
Article
Self-assembled fibrillar network hydrogels and organogels are commonly obtained through a crystallization process as fibers upon being induced by external stimuli such as temperature or pH. The gel-to-sol-to-gel transition is generally readily reversible, and the rate of change of the stimulus determines the fiber homogeneity and eventual elastic p...
Preprint
Self-assembled fibrillar network (SAFIN) hydrogels and organogels are commonly obtained by a crystallization process into fibers induced by external stimuli like temperature or pH. The gel-to-sol-to-gel transition is generally readily reversible and the change rate of the stimulus determines the fiber homogeneity and eventual elastic properties of...
Chapter
Within the bio-economy, more specifically within the bio-based industries, biomass feedstock – in contrast to fossil feedstocks in the fossil-based economy – is converted into the so-called bio-based products such as biosurfactants, bioplastics, pharmaceuticals, paper, textiles, and biofuels using either chemical or biological production methods or...
Article
Full-text available
Yeast-derived bola amphiphiles have attracted growing attention in various industrial sectors as green reagents. However, their physico-chemical properties relevant to mineral separation by froth flotation are poorly explored. To bridge this gap, we studied the foaming, interfacial, and flotation properties of acidic sophorolipid (ASL), acidic gluc...
Article
Full-text available
Biodegradable and biobased surface active agents are renewable and environmentally friendly alternatives to petroleum derived or oleochemical surfactants. However, they are accompanied by relatively high production costs. In this study, the aim was to reduce the production costs for an innovative type of microbial biosurfactant: bolaform sophorolip...
Article
The yeast Starmerella bombicola distinguishes itself from other yeasts by its potential of producing copious amounts of the secondary metabolites sophorolipids (SLs): these are glycolipid biosurfactants composed out of a(n) (acetylated) sophorose moiety and a lipid tail. Although SLs are the subject of numerous research papers and have been commerc...
Article
Nanofibres are an interesting phase into which amphiphilic molecules can self-assemble. Described for a large number of synthetic lipids, they were seldom reported for natural lipids like microbial amphiphiles, known as biosurfactants. In this work, we show that the palmitic acid congener of sophorolipids (SLC16:0), one of the most studied families...
Article
Secondary/waste streams have previously been used as feedstocks to produce sophorolipids (SLs), a biosurfactant with low eco-toxicity and high biodegradability, in order to reduce production costs and protect the environment. However, limited productivities and titres from these feedstocks remain as important challenges. Thus, the optimisation of f...
Article
Sophorolipids are biobased compounds produced by the genera Starmerella and Pseudohyphozyma that gain exponential interest from academic and industrial stakeholders due to their mild and environmental friendly characteristics. Currently, industrially relevant sophorolipid productivities are reached up to 3.7 g∙L-1∙h-1 and sophorolipids are used in...
Article
Bioconversion of food waste into sophorolipid-based biosurfactants is a promising emerging technology. It is important to evaluate the environmental impacts associated with the latest advancements in sophorolipid production as it matures to maximize sustainability on scale-up. This study takes a dynamic Life Cycle Assessment (dLCA) approach to addr...
Article
Full-text available
Chemical surfactants are omnipresent in consumer products, but they are the subject of environmental concerns. For this reason, the complete replacement of petrochemical surfactants by biosurfactants constitutes a holy grail, but this is far from possible in the near future. Although the “biosurfactants revolution” has not yet occurred, mainly due...
Preprint
Full-text available
Chemical surfactants are omnipresent in consumers' products but they suffer from environmental concerns. For this reason, complete replacement of petrochemical surfactants by biosurfactants constitute a holy grail but this is far from occurring any soon. If the "biosurfactants revolution" has not occurred, yet, mainly due to the higher cost and low...
Preprint
Nanofibers are an interesting phase into which amphiphilic molecules can self-assemble. Described for a large number of synthetic lipids, they were seldom reported for natural lipids like microbial amphiphiles, known as biosurfactants. In this work, we show that the palmitic acid congener of sophorolipids (SLC16:0), one of the most studied families...
Article
Full-text available
With the global demand for economically important metals increasing, compounded by the depletion of readily accessible ores, secondary resources and low-grade ores are being targeted to meet growing demands. Novel technologies developed within biobased industries, such as microbial biosurfactants, could be implemented to improve the sustainability...
Article
Microbial biosurfactants are surface-active molecules that are naturally produced by a range of microorganisms. They have certain advantages over chemical surfactants, such as lower toxicity, higher biodegradability, anti-tumor, and anti-microbial properties. Sophorolipids (SLs) in particular are one of the most promising biosurfactants, as they ho...
Article
Full-text available
Sophorolipids are one of the most important microbial biosurfactants, because of their large-scale production and applications developed so far in the fields of detergency, microbiology, cosmetics or environmental science. However, the structural variety of native sophorolipids is limited/restricted, a limiting fact for the development of new prope...
Article
Full-text available
The demand for microbially produced surface-active compounds for use in industrial processes and products is increasing. As such, there has been a comparable increase in the number of publications relating to the characterization of novel surface-active compounds: novel producers of already characterized surface-active compounds and production proc...
Preprint
Full-text available
Sophorolipids are one of the most important microbial biosurfactants, because of their large-scale production and applications developed so far in the fields of detergency, microbiology, cosmetics or environmental science. However, the structural variety of native sophorolipids is limited/restricted, a limiting fact for the development of new prope...
Article
Glycosylated surfaces can display antimicrobial properties. It has been shown that sophorolipids can be used to develop biocidal coatings against Gram-positive and Gram-negative bacteria, but with a limited efficiency so far. Therefore, it appears necessary to further investigate the surface antibacterial activity of a broader set of structurally r...
Preprint
div>Glycosylated surfaces can display antimicrobial properties. It has been shown that sophorolipids can be used to develop biocidal coatings against Gram-positive and Gramnegative bacteria, but with a limited efficiency so far. Therefore, it appears necessary to further investigate the surface antibacterial activity of a broader set of structurall...
Article
Starmerella bombicola very efficiently produces the secondary metabolites sophorolipids (SLs). Their biosynthesis is not-growth associated and highly upregulated in the stationary phase. Despite high industrial and academic interest, the underlying regulation of SL biosynthesis remains unknown. In this paper, potential regulation of SL biosynthesis...
Article
Lipid lamellar hydrogels are rare soft fluids composed of a phospholipid lamellar phase instead of fibrillar networks. The mechanical properties of these materials are controlled by defects, induced by local accumulation of a polymer or surfactant in a classical lipid bilayer. Herein we report a new class of lipid lamellar hydrogels composed of one...
Article
This study evaluates the techno-economic feasibility of sophorolipid (SL) production process that co-utilizes food waste, glucose and oleic acid as substrates. Two variables are considered in terms of (a) Plant construction: Purchasing equipment either from the US or Mainland China and (b) Production: to produce SL crystals (about 97% active) or a...
Article
Full-text available
The United Nations’ Sustainable Development Goals have sparked growing interest in biosurfactants from many surfactant-loaded industries including those utilizing froth flotation for mineral separation. However, the interaction of biosurfactants with mineral surfaces is currently poorly understood. We bridge this gap by studying adsorption of a yea...
Article
To decrease our dependency for the diminishing source of fossils resources, bio-based alternatives are being explored for the synthesis of commodity and high-value molecules. One example in this ecological initiative is the microbial production of the biosurfactant sophorolipids by the yeast Starmerella bombicola. Sophorolipids are surface-active m...
Article
Glucolipids (GLs) are glycolipid biosurfactants with promising properties. These GLs are composed of glucose attached to a hydroxy fatty acid through a ω and/or ω‐1 glycosidic linkage. Up until today these interesting molecules could only be produced using an engineered Starmerella bombicola strain (∆ugtB1::URA3 G9) producing GLs instead of sophoro...
Article
Until now, the production of microbial biosurfactants has been limited to the use of first-generation (food) substrates. Moreover, the results on sophorolipids yield and productivity reported by state-of-the-art fed-batch processes for sophorolipids production remain unsatisfactory and lead to a significantly high cost per kg of the product. With a...
Article
To reduce environmental and occupational impact of flotation reagents, there is an emerging need to find greener reagents for sulphide mineral flotation. This study presents a comparison of the interactions of chalcopyrite with three glycolipid biosurfactants (sophorolipid, glucolipid and glucoside) and three traditional thiol surfactants (collecto...
Article
The compartmentalization of colloids into topologically closed, vesicular, microphases offers an attractive mean to concentrate a functional cargo in aqueous solutions for a range of biomedical, cosmetic, and biotechnological applications. In this paper, we develop a simple, phospholipid‐free, phase change method employing a pH‐responsive glycolipi...
Preprint
Full-text available
Lipid lamellar hydrogels are rare soft fluids composed of a phospholipid lamellar phase instead of isotropic fibrillary networks. The mechanical properties of these thermodynamic materials are controlled by defects, induced by local accumulation of a polymer or surfactant. In this work, we present a new class of kinetically-trapped, lipid lamellar...
Article
Control of the nucleation and growth process in self-assembled fibrillary networks (SAFiN) with the goal of preparing physical hydrogels from low-molecular-weight gelators (LMWG) is well established but mainly for temperature-driven hydrogelators. In the presence of other stimuli, such as pH, the fundamental knowledge behind gel formation is still...
Article
Full-text available
Both strain engineering and process optimization are intensively studied in microbial biosurfactant literature. However, screening of multiple strains and/or medium components in parallel is a very labor-intensive and timely process, considering the only applied technique nowadays is evaluation through shake flask and/or bioreactor experiments. The...
Article
Twelve new quaternary ammonium sophorolipids with long alkyl chains on the nitrogen atom were synthesized starting from oleic and petroselinic acid based sophorolipids. These novel derivatives were evaluated for their antimicrobial activity against selected Gram‐negative and Gram‐positive bacteria and their transfection efficacies on three differen...
Article
Recent sustainable development goals of food security, environmental protection, material and energy efficiency are the key drivers of the valorization of food waste. In the present work, the production of biosurfactant sophorolipids from several (food) waste streams was investigated, using the non-pathogenic yeast Starmerella bombicola. From a pre...
Article
Conventional head-chain but also more exotic divalent, Gemini, or bolaform amphiphiles have in common well-defined hydrophilic and hydrophobic blocks with often a predictable self-assembly behavior. However, new categories of amphiphiles, such as microbial biosurfactants, challenge such conventional understanding because of the poorly defined bound...
Article
Full-text available
By means of single-cell force nanoscopy we show that sophorolipid biosurfactants feature unusually strong antiadhesion properties against nosocomial pathogens involved in catheter-related infections.
Article
Full-text available
Sophorolipids is one of the most extensively studied microbial biosurfactants. Starmerella bombicola is the most productive strain known for sophorolipid production with volumetric productivity of up to 3.7g/(L∙h). This review focuses on the two most important aspects that have an influence on sophorolipid commercialization. Firstly, the metabolic...
Article
Full-text available
Sophorolipids are one of the best known microbial biosurfactants and are produced by several yeast species. The best studied producer is Starmerella bombicola, a non-pathogenic yeast associated in nature with bumblebees. Sophorolipids are built up of the rare disaccharide sophorose, which is attached to a fatty acid through a glyosidic bound. Sopho...
Article
A bio-based glycolipid bolaamphiphile (glyco-bolaamphiphile) has recently been produced (Van Renterghem et al., Biotechnol. Bioeng., 2018, 115, 1195–1206) on a gram scale by using the genetically-engineered S. bombicola strain Δat Δsble Δfao1. The glyco-bolaamphiphile bears two symmetrical sophorose headgroups at the extremities of a C16:0 (ω-1 hyd...
Article
In this review, we focus on one of the most important microbial producers of biosurfactants, Starmerella bombicola. Emphasis is laid on the discovery, taxonomy, habitat, cellular characteristics, biochemistry and genetics of this non-pathogenic yeast. Biosurfactants are natural surface-active compounds produced by several types of microorganisms an...
Article
Complex coacervation of polyelectrolytes with surfactant micelles is a promising system for a wide range of applications. However, the development of “green coacervates” from bio-based surfactants and biopolymers has not yet been explored. Herein, complex coacervation of micelles from a bolaform sophorolipid biosurfactant with oppositely charged ca...
Article
New synthetic pathways are proposed for the synthesis of a new set of bolaamphiphilic derivatives starting from microbiologically produced sophorolipids. A total set of 43 new derivatives was synthesized via reductive amination of a previously synthesized sophorolipid aldehyde with diamines and primary amines. The new derivatives were evaluated for...
Chapter
In this chapter, a step-by-step approach on how to transform non-conventional yeasts or fungi into platform organisms is described. The non-conventional glycolipid producing yeast Starmerella bombicola (and in some cases also Pseudohyphozyma bogoriensis) is used as a case study. And more specifically how to engineer it toward production of new-to-n...
Article
Glycolipid microbial biosurfactants, like 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...
Article
Aims: To assess the efficacy of rhamnolipid (mixture of mono- and di-rhamnolipid congeners, purified monorhamnolipid, dirhamnolipid and lactonic sophorolipid biosurfactants against pathogens important for oral hygiene. Methods and results: Acquired and produced biosurfactants were fully characterised to allow the antimicrobial activity to be ass...
Article
Full-text available
Vesicle-in-vesicle self-assembled containers, or vesosomes, are promising alternatives to liposomes because of their possible hierarchical encapsulation and high stability. We report herein the first example of sugar-based vesicles-in-vesicles, which we baptize glucosomes. These were prepared by using a natural microbial glycolipid (branched C22 so...
Article
Sophorolipids (SLs), a class of microbially derived biosurfactants, are reported by different research groups to have different self-assembled structures (either micelles or giant ribbons) under the same conditions. Here we explore the reasons behind these contradictory results and attribute these differences to the role of specific congeners that...
Article
Microbial production of biosurfactants represents one of the most interesting alternatives to classical petrol-based compounds due to their low toxicity, high biodegradability, and biological production processes from renewable bioresources. However, some of the main drawbacks generally encountered are the low productivities and the small number of...
Article
Full-text available
We recently discovered a novel enzyme in the exoproteome of Starmerella bombicola, which is structurally related to Candida antarctica lipase A. A knockout strain for this enzyme does no longer produce lactonic sophorolipids, prompting us to believe that this protein is the missing S. bombicola lactone esterase (SBLE). SBLE catalyzes a rather unusu...
Article
Full-text available
Biosurfactants are of growing interest as sustainable alternatives to fossil-fuel-derived chemical surfactants, particularly for the detergent industry. To realize this potential, it is necessary to understand how they affect proteins which they may encounter in their applications. However, knowledge of such interactions is limited. Here, we presen...
Article
A set of four structurally related glycolipids are described: two of them have one glucose unit connected to either stearic or oleic acid, and two other ones have a diglucose headgroup (sophorose) similarly connected to either stearic or oleic acid. The self-assembly properties of these compounds, poorly known, are important to know due to their us...
Article
Production scale-up of high purity diacetylated C18:1 sophorolipid lactone was demonstrated from lab to pilot scale with the Starmerella bombicola lactone esterase overexpression strain (oe sble) as production organism. The 150 L fermentation using oleic acid and yeast extract, characterized by a titer of 199 g/L and a volumetric productivity of 0....
Article
Microbial glycolipids are a class of well-known compounds, but their self-assembly behavior is still not well understood. While the free carboxylic acid end group makes some of them interesting stimuli-responsive compounds, the sugar hydrophilic group and the nature of the fatty acid chain make the understanding of their self-assembly behavior in w...
Article
Full-text available
Sophorolipids (SL) are amphiphilic biosurfactant molecules consisting of a disaccharide sophorose with one fatty acid at the C1 position and optional acetylation at the C6’and C6” positions. They exist in a closed ring lactonic (LSL) or open acidic (ASL) structure Sophorolipids are produced in crude mixtures in economically viable amounts by the ye...
Data
LSL treatment results in the detachment of dead cells. Quantification of live or dead cells using propidium iodide and Syto 9 staining on cells extracted from the supernatant of cultures treated with 0, 50 or 100μg/ml of LSL. Following treatment with 50μg/ml LSL, CCD-84l CoN (a), all detached cells in the supernatant were dead (*** p <0.001). At th...
Article
Sophorolipids (SL) are amphiphilic biosurfactant molecules consisting of a disaccharide sophorose with one fatty acid at the C1 position and optional acetylation at the C6’and C6” positions. They exist in a closed ring lactonic (LSL) or open acidic (ASL) structure Sophorolipids are produced in crude mixtures in economically viable amounts by the ye...
Article
Bola-amphiphilic surfactants are molecules with fascinating properties. Their unique configuration consisting of a long hydrophobic spacer connecting two hydrophilic entities renders the molecule more water soluble than the average surfactant, but still allows formation of supramolecular structures. These properties make them extremely suitable for...
Conference Paper
Full-text available
In the European chemical industry, there is a strong drive to shift from fossil to renewable resources in the pursuit of sustainability. Sophorolipids, a class of biosurfactants, are interesting renewable resources, since they combine a complex structure with divergent biological and physico-chemical properties. The microbially produced lactonic so...
Article
Although sophorolipids (SLs) produced by S. bombicola are a real showcase for the industrialization of microbial biosurfactants, some important drawbacks are associated with this efficient biological process, e.g. the simultaneous production of acidic and lactonic SLs. Depending on the application, there is a requirement for the naturally produced...
Article
Biosurfactants (BSs) are a class of secondary metabolites representing a wide variety of structures that can be produced from renewable feedstock by a wide variety of micro-organisms. They have (potential) applications in the medical world, personal care sector, mining processes, food industry, cosmetics, crop protection, pharmaceuticals, bio-remed...