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... more
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 through the telomere positioning effect (TPE) was investigated, as the SL gene cluster is located adjacent to a telomere. An additional copy of this gene cluster was introduced elsewhere in the genome to investigate if this results in a decoy of regulation. Indeed, for the new strain, the onset of SL production was shifted to the exponential phase. This result was confirmed by RT-qPCR analysis. The TPE effect was further investigated by developing and applying a suitable reporter system for this non-conventional yeast, enabling non-biased comparison of gene expression between the subtelomeric CYP52M1- and the URA3 locus. This was done wit...
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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)... more
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 commercialized, e.g., in eco-friendly cleaning solutions, the natural function of SLs still remains elusive. This research article investigates several hypotheses for why S. bombicola invests that much energy in the production of SLs, and we conclude that the main natural function of SLs in S. bombicola is niche protection: (1) the extracellular storage of an energy-rich, yet metabolically less accessible carbon source that can be utilized by S. bombicola upon conditions of starvation with (2) antimicrobial properties. In this way, S. bombicola creates a dual advantage in competition with other microorganisms. Additionally, SLs can expedite growt...
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In situ product recovery (ISPR), in the form of an extractive fermentation process, can increase productivity and product titers in the sustainable production of platform chemicals. To establish a guideline for the development of... more
In situ product recovery (ISPR), in the form of an extractive fermentation process, can increase productivity and product titers in the sustainable production of platform chemicals. To establish a guideline for the development of industrially relevant production processes for such bio-based compounds, a wide screening was performed, mapping the potential of an extensive range of solvents and solvent mixtures. Besides solvent biocompatibility with Saccharomyces cerevisiae, distribution coefficients of three organic acids (protocatechuic acid, adipic acid and para-aminobenzoic acid) and four fragrance compounds (2-phenylethanol, geraniol, trans-cinnamaldehyde and β-ionone) were determined. While for highly hydrophobic fragrance compounds, multiple pure solvents were identified that were able to extract more than 98%, reactive extraction mixtures were proven effective for more challenging compounds including organic acids and hydrophilic alcohols. For example, a reactive mixture consis...
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Resistance of pathogenic microorganisms against antimicrobials is a major threat to contemporary human society. It necessitates a perpetual influx of novel antimicrobial compounds. More specifically, Gram− pathogens emerged as the most... more
Resistance of pathogenic microorganisms against antimicrobials is a major threat to contemporary human society. It necessitates a perpetual influx of novel antimicrobial compounds. More specifically, Gram− pathogens emerged as the most exigent danger. In our continuing quest to search for novel antimicrobial molecules, alkaloids from marine fungi show great promise. However, current reports of such newly discovered alkaloids are often limited to cytotoxicity studies and, moreover, neglect to discuss the enigma of their biosynthesis. Yet, the latter is often a prerequisite to make them available through sufficiently efficient processes. This review aims to summarize novel alkaloids with promising antimicrobial properties discovered in the past five years and produced by marine fungi. Several discovery strategies are summarized, and knowledge gaps in biochemical production routes are identified. Finally, links between the structure of the newly discovered molecules and their activity ...
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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... more
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 structurally related glycolipids.The present work explores the influence of the glucosidic moiety (gluco-, sophoro-, cellobio-)and the fatty acid backbone (saturated, cis or trans monounsaturated). We show that the fattyacid backbone plays an important role: cis derivative of sophorolipids (SL) grafted onto modelgold surfaces has better biocidal properties than saturated (SL0) and trans monounsaturated(SLt) molecules, which appear to be inefficient. The number of glucose units is also a key factor:a one-third decrease in antibacterial activity is observed when having one glucose unit (GL)compared to two (SL).Sugar acetylation (SLa) does not seem to have ...
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Microbial enzymes are used today in the most diverse industrial sectors. However, it is only in recent years that fundamental knowledge has been acquired that allows for a rational ? rather than an empirical ? development and application... more
Microbial enzymes are used today in the most diverse industrial sectors. However, it is only in recent years that fundamental knowledge has been acquired that allows for a rational ? rather than an empirical ? development and application of microbial enzyme processes. These enzymes are primarily used as an end product or a processing aid in the agricultural sector, food and feed industry, the detergent sector, the textile industry and health care sector. In these sectors they replace or adjust the familiar (bio)chemical processes, or plant or animal enzymes. But they can also perform totally new ?chemical? reactions, with the principal aim of ?improving? and/or modifying the ?substrate?.
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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... more
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. Sophorolipids produced by S. bombicola mainly contain oleic acid as the incorporated hydrophobic group. Other chain lengths can, to a certain content, be incorporated by feeding the yeast with substrates of alternative chain lengths. However, the efficiency for such substrates is low as compared to the preferred C18 chain length and defined by the substrate specificity of the first enzymatic step in sophorolipid biosynthesis, i.e., the cytochrome P450 enzyme CYP52M1. To increase product uniformity and diversity at the same time, a new strain of S. bombicola was developed that produces sophorolipids with a palmitic acid acyl chain. This was achi...
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Steviol glycosides from the leaves of the plant Stevia rebaudiana are high-potency natural sweeteners but suffer from a lingering bitterness. The Lactobacillus reuteri 180 wild-type glucansucrase Gtf180-ΔN, and in particular its... more
Steviol glycosides from the leaves of the plant Stevia rebaudiana are high-potency natural sweeteners but suffer from a lingering bitterness. The Lactobacillus reuteri 180 wild-type glucansucrase Gtf180-ΔN, and in particular its Q1140E-mutant, efficiently α-glucosylated rebaudioside A (RebA), using sucrose as donor substrate. Structural analysis of the products by MALDI-TOF mass spectrometry, methylation analysis and NMR spectroscopy showed that both enzymes exclusively glucosylate the Glc(β1→C-19 residue of RebA, with the initial formation of an (α1→6) linkage. Docking of RebA in the active site of the enzyme revealed that only the steviol C-19 β-D-glucosyl moiety is available for glucosylation. Response surface methodology was applied to optimize the Gtf180-ΔN-Q1140E-catalyzed α-glucosylation of RebA, resulting in a highly productive process with a RebA conversion of 95% and a production of 115 g/L α-glucosylated products within 3 h. Development of a fed-batch reaction allowed fur...
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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,... more
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 types of molecules by S. bombicola, like the 'non-symmetrical bolaform (nsBola) SLs'. As classic SLs are mostly applied in eco-friendly detergents, the possible use of these bolaform SLs in detergent applications was evaluated by scaling up the production process (150 L) and evaluating the purified product. This paper shows that they can be used as green and non-irritant surfactants in for example (automatic) dishwasher applications. However, the limited chemical stability at higher pH values (> 6.5), due to the presence of an ester function in the biosurfactant molecule, is a major drawback that will most likely inhibit market ...
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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... more
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 unusual reaction, i.e., an intramolecular esterification (lactonization) of acidic sophorolipids in an aqueous environment, which raised questions about its activity and mode of action. Here, we report the heterologous production of this enzyme in Pichia pastoris and its purification in a two-step strategy. Purified recombinant SBLE (rSBLE) was used to perform HPLC and liquid chromatography mass spectrometry (LCMS)-based assays with different sophorolipid mixtures. We experimentally confirmed that SBLE is able to perform ring closure of acetylated acidic sophorolipids. This substrate was selected for rSBLE kinetic studies to estimate the appare...
Research Interests: Kinetics, Mass Spectrometry, Gene expression, Multidisciplinary, Temperature, and 10 moreHigh Pressure Liquid Chromatography, Applied Microbiology and Biotechnology, Molecular cloning, Glycolipids, Protein Conformation, Amino Acid Substitution Rates, Recombinant Proteins, Hydrogen-Ion Concentration, Site-directed Mutagenesis, and Lactones
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... more
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 applications in in nanotechnology, electronics and gene and drug delivery. In general, these compounds are obtained by chemical synthesis. We report here an efficient microbial production process for the fully green synthesis of bolaform surfactants. A sophorolipid producing Starmerella bombicola yeast strain was disabled in its sophorolipid acetyltransferase and lactone esterase, which should logically result in synthesis of non-acetylated acidic sophorolipids; molecules with the classic amphiphilic structure. Surprisingly, also bolaform glycolipids were obtained, with an additional sophorose linked to the free carboxyl end of the acidic sophorolipids as confirmed by MS and NMR analysis. The obtained titres of 27.7 g/L total product are comparable to wild-type values, and the novel molecules account for at least 74% of this. Bola-amphiphile biosynthesis proved to be attributed to the promiscuous activity of both UDP-glucosyltransferases UGTA1 and UGTB1 from the core sophorolipid pathway displaying activity towards non-acetylated intermediates. The absence of acetyl groups seems to trigger formation of bolaform compounds starting from acidic sophorolipids. Hence, wild type Starmerella bombicola produces these compounds only at marginal amounts in general not reaching detection limits. We created a strain knocked-out in its sophorolipid acetyltransferase and lactone esterase able to produce these novel compounds in economical relevant amounts, opening doors for the application of biological derived bolaform structures. This article is protected by copyright. All rights reserved.
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α-d-Galactose 1-phosphate (αGal1P) is an important building block for the synthesis of nucleotide sugars that are substrates for glycosyltransferases. We have previously reported the creation of novel lactose phosphorylase enzymes that... more
α-d-Galactose 1-phosphate (αGal1P) is an important building block for the synthesis of nucleotide sugars that are substrates for glycosyltransferases. We have previously reported the creation of novel lactose phosphorylase enzymes that are useful for the synthesis of αGal1P from the cheap and abundant lactose. Here we describe the application of such a lactose phosphorylase in a production system using permeabilized Escherichia coli cells. After purification of the product from the reaction mixture by anion-exchange chromatography and ethanol precipitation, 9.5 grams of highly pure αGal1P were obtained from a 1 l reaction volume.
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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... more
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 water not easy and highly unpredictable. Using cryo-transmission electron microscopy (cryo-TEM) and both pH-dependent in situ and ex situ small angle X-ray scattering (SAXS), we demonstrate that the aqueous self-assembly at room temperature (RT) of a family of β-d-glucose microbial glycolipids bearing a saturated and monounsaturated C18 fatty acid chain cannot be explained on the simple basis of the well-known packing parameter. Using the "pH-jump" process, we find that the molecules bearing a monosaturated fatty acid forms vesicles below pH 6.2, as expected, but the derivative with a saturated fatty acid forms infinite bilayer sh...
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A formerly unknown nucleotide pyrophosphatase/phosphodiesterase (NPP) of wheat (Triticum aestivum L.) (TaNPP) was recombinantly produced in Pichia pastoris (TaNPPr) following assembly of the sequence out of wheat ESTs using sequences of... more
A formerly unknown nucleotide pyrophosphatase/phosphodiesterase (NPP) of wheat (Triticum aestivum L.) (TaNPP) was recombinantly produced in Pichia pastoris (TaNPPr) following assembly of the sequence out of wheat ESTs using sequences of known NPPs. Simultaneously, a phosphodiesterase was purified to homogeneity from wheat germs, characterised and identified as TaNPP. TaNPP contains the highly conserved catalytic substrate and metal binding residues and
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Petroselinic acid, a positional isomer of oleic acid, was isolated from the vegetable oil of Coriandrum sativum fruits. This uncommon fatty acid was subsequently used as substrate for sophorolipid fermentation with a Starmerella bombicola... more
Petroselinic acid, a positional isomer of oleic acid, was isolated from the vegetable oil of Coriandrum sativum fruits. This uncommon fatty acid was subsequently used as substrate for sophorolipid fermentation with a Starmerella bombicola lactone esterase overexpression (oe sble) strain. A petroselinic acid based diacetylated sophorolipid lactone was obtained in high purity without incorporation of de novo synthesized fatty acids such as oleic acid. A total production of 40 g/L was obtained. The petroselinic acid based sophorolipid lactone was subsequently hydrolyzed towards the petroselinic acid based sophorolipid acid. For both compounds, their critical micelle concentration (CMC) and corresponding surface tension were compared to their oleic acid based counterparts. Both petroselinic acid based sophorolipids displayed a much lower CMC value than their oleic acid based counterparts, although their minimal surface tension was the same. Besides, the sophorolipid fermentation product...
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ABSTRACT Broad spectrum producing hosts and fundamental research models such as yeast can only be developed if one can rely both on sophisticated engineering techniques, as for example required in the emerging fields of synthetic biology... more
ABSTRACT Broad spectrum producing hosts and fundamental research models such as yeast can only be developed if one can rely both on sophisticated engineering techniques, as for example required in the emerging fields of synthetic biology and combinatorial engineering, and consistent basic molecular tools [1]. One of these basic tools needed for any type of genetic engineering is a quick and reliable method for screening transformants. In this study nine colony PCR methods were tested for the amplification of plasmid or chromosomal DNA from fresh and older colonies of Saccharomyces cerevisiae. The methods involved boiling in NaOH [2] or in cracking buffer, freeze-thawing in lysis buffer [3] or in the microwave oven [4], SDS treatment [5], heating in the microwave oven [6], spheroplast preparation [7], fast preparation of fungal DNA described by Liu et al. [8], and the use of untreated yeast cells in the PCR. For fresh colonies, freeze-thawing cycles (-20 textdegree C/microwave oven) gave the most relable results, obtaining fragments up to 1 kb and 2 kb from plasmid and chromosomal DNA, respectively. With older cells, amplification of 3 kb genomic DNA fragments and 1 kb plasmid DNA fragments was consistently achieved by heating cells in the microwave oven. As for the addition PCR enhancing agents, it can be concluded that betain or triton are more beneficial than tween. 1. Roberts, I.N. and S.G. Oliver. Biotechnology Letters, 2011. 33(3): p. 477-487. 2. Wang, H., S.E. Kohalmi, and A.J. Cutler. Analytical Biochemistry, 1996. 237(1): p. 145-146. 3. Harju, S., H. Fedosyuk, and K.R. Peterson. Bmc Biotechnology, 2004. 4. 4. The Murray Lab from: http://www.mcb.harvard.edu/murray/colony_pcr.html. 5. Akada, R., T. Murakane, and Y. Nishizawa. Biotechniques, 2000. 28(4): p. 668-+. 6. Lisby, M. from: www1.bio.ku.dk/english/research/fg/transkription/resources/protocols/colonypcr/. 7. Ling, M.F., F. Merante, and B.H. Robinson. Nucleic Acids Research, 1995. 23(23): p. 4924-4925. 8. Liu, K.H., Y.L. Yeh, and W.C. Shen. Journal of Microbiological Methods, 2011. 85(2): p. 170-172.
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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... more
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 mixture to be manipulated to give defined ratios of the components. Recently, the enzyme responsible for the lactonization of SLs was discovered. The discovery of the gene encoding this lactone esterase (sble) enabled the development of promising S. bombicola strains producing either solely lactonic (using a sble overexpression strain described in this paper: oe sble) or solely acidic SLs (using a sble deletion strain, which was recently described, but not characterized yet: Δsble). The new S. bombicola strains were used to investigate the production processes (fermentation and purification) of either lactonic or acidic SLs. The strains maintain the high inherent productivities of the wild-type or even perform slightly better and thus represent a realistic industrial opportunity. 100% acidic SLs with a mixed acetylation pattern were obtained for the Δsble strain, while the inherent capacity to selectively produce lactonic SLs was significantly increased (+42%) for the oe sble strain (99% lactonic SLs). Moreover, the regulatory effect of citrate on lactone SL formation for the wild-type was absent in this new strain, which indicates that it is more robust and better suited for the industrial production of lactonic SLs. Basic parameters were determined for the purified SLs, which confirm that the two new strains produce molecules with distinctive properties of which the application potential can now easily be investigated independently. Biotechnol. Bioeng. 2015;9999: 1-10. © 2015 Wiley Periodicals, Inc.
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Isoflavonoid representatives such as genistein, daidzein are high potent anti-cancer, anti-bacterial, anti-oxidant agents. It have been demonstrated that methylation of flavonoids enhanced the transporting ability, which lead to... more
Isoflavonoid representatives such as genistein, daidzein are high potent anti-cancer, anti-bacterial, anti-oxidant agents. It have been demonstrated that methylation of flavonoids enhanced the transporting ability, which lead to facilitated absorption and greatly increased bioavailability. In this paper, genetically engineered Escherichia coli was reconstructed by harboring E. coli K12-derived metK encoding S-adenosylmethionine (SAM) synthase (accession number: K02129) for enhancement of SAM as precursor and a Streptomyces avermitilis-originated SaOMT2 (O-methyltransferase, accession number: NP_823558) for methylation of daidzein and genistein as preferred substrates. The formation of desired products via biotransformation including 7-O-methyl-genistein and 7-O-methyl-daidzein were confirmed individually by chromatographical data such as HPLC, LC-TOF-MS and NMR ((1) H and (13) C) as well. Furthermore, substrates concentration, incubation time and media parameters were optimized using flask culture. Finally, the most fit conditions were applied for fed-batch fermentation with scale up to 3 L (working volume) to obtain the maximum yield of the products including 164.25 μM (46.81 mg/L) and 382.50 μM (102.88 mg/L) for 7-O-methyl genistein and 7-O-methyl daidzein, respectively. In particular, potent inhibitory activities of those isoflavonoid methoxides against the growth of cancer line (B16F10, AGS and HepG2) and endothelical (HUVEC) cells were investigated and demonstrated. Taken together this research work described the production of isoflavonoid-7-O-methoxides by E. coli engineering, improvement of production, characterization of produced compounds and preliminary in vitro biological activities of the these flavonoids being manufactured. This article is protected by copyright. All rights reserved.
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UDP-sugar 4-epimerase (GalE) belongs to the short-chain dehydrogenase/reductase (SDR) superfamily of proteins and is one of enzymes in the Leloir pathway. They have been shown to be important virulence factors in a number of Gram-negative... more
UDP-sugar 4-epimerase (GalE) belongs to the short-chain dehydrogenase/reductase (SDR) superfamily of proteins and is one of enzymes in the Leloir pathway. They have been shown to be important virulence factors in a number of Gram-negative pathogens and to be involved in the biosynthesis of different polysaccharide structures. The metabolic disease type III galactosemia is caused by detrimental mutations in the human GalE. GalE and related enzymes display unusual enzymologic, chemical, and stereochemical properties; including irreversible binding of the cofactor NAD and uridine nucleotide-induced activation of this cofactor. These epimerases have been found active on UDP-hexoses, the N-acetylated and uronic acid forms thereof as well as UDP-pentoses. As they are involved in different pathways and functions, a deeper understanding of the enzymes, and their substrate promiscuity and/or selectivity, could lead to drug and vaccine design as well as antibiotic and probiotic development. This review summarizes the research performed on UDP-sugar 4-epimerases' structure, mechanism and substrate promiscuity.
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ABSTRACT
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ABSTRACT The aim of this work was to evaluate the physical–chemical properties of blends of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and a medium-chain-length polyhydroxyalkanoate (LA). Blends were obtained by casting... more
ABSTRACT The aim of this work was to evaluate the physical–chemical properties of blends of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and a medium-chain-length polyhydroxyalkanoate (LA). Blends were obtained by casting film-solution on leveled trays. Morphological analysis showed compatibility between the two polymers up to 5 g/100 g of LA polymer was added and phase separation in the polymeric system for compositions containing more than 5 g/100 g of LA polymer. TGA data and glass transition temperatures revealed some compatibility of the polymers. Moreover, there is a significant decrease of melting temperature and elasticity modulus for PHBV–LA blends with composition. Films containing 5 g/100 g of LA polymer showed an improvement of 50% in elongation to break (SB) when compared with pure PHBV. For other samples the SB decreased most likely due to the lack of adhesion between the two polymeric phases.
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D-Mannitol is a sugar alcohol with many applications in food, pharmaceuticals, medicine, and chemistry. Mannitol crystallizes in small white needles with a melting point of 165170 C. Mannitol has a sweet cool taste owing to its high... more
D-Mannitol is a sugar alcohol with many applications in food, pharmaceuticals, medicine, and chemistry. Mannitol crystallizes in small white needles with a melting point of 165170 C. Mannitol has a sweet cool taste owing to its high negative heat of solution (121 kJ/kg). ...
In the recent years, biosurfactants proved to be an interesting alternative to petrochemically derived surfactants. Two classes of biosurfactants, namely glycolipids and lipopeptides, have attracted significant commercial interest.... more
In the recent years, biosurfactants proved to be an interesting alternative to petrochemically derived surfactants. Two classes of biosurfactants, namely glycolipids and lipopeptides, have attracted significant commercial interest. Despite their environmental advantages and equal performance, commercialization of these molecules remains a challenge due to missing acquaintance of the applicants, higher price and lack of structural variation. The latter two issues can partially be tackled by screening for novel and better wild-type producers and optimizing the fermentation process. Yet, these traditional approaches cannot overcome all hurdles. In this review, an overview is given on how biotechnology offers opportunities for increased biosurfactant production and the creation of new types of molecules, in this way enhancing their commercial potential.
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Sophorolipids produced by the non-pathogenic yeast Candida bombicola ATCC 22214 are glycolipid biosurfactants applied commercially as biodegradable and eco-friendly detergents. Their low cell toxicity, excellent wetting capability and... more
Sophorolipids produced by the non-pathogenic yeast Candida bombicola ATCC 22214 are glycolipid biosurfactants applied commercially as biodegradable and eco-friendly detergents. Their low cell toxicity, excellent wetting capability and antimicrobial activity attract the attention of high-value markets, such as the cosmetic and pharmaceutical industries. Although sophorolipid production yields have been increased by the optimization of fermentation parameters and feed sources, the biosynthetic pathway and genetic mechanism behind sophorolipid production still remains unclear. Here we identify a UDP-glucosyltransferase gene, UGTB1, with a key function in this economically important pathway. The protein shows sequence and structural homology to several bacterial glycosyltransferases involved in macrolide antibiotic synthesis. Deletion of UGTB1 in C. bombicola did not affect cell growth and resulted in a yeast producing glucolipids, thereby opening the route for in vivo production of the...