Molecular weight dependent structure of the exopolysaccharide levan

Hundschell, Christoph Simon; Jakob, Frank; Wagemans, Anja Maria

doi:10.1016/j.ijbiomac.2020.06.019

Cited by 26 publications

(16 citation statements)

References 53 publications

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“…Previous studies revealed that the spherical high molecular weight levan molecules produced by G. albidus TMW 2.1191 are functionally diverse regarding their hydrocolloid and rheological properties depending on their molecular size (Hundschell et al 2019(Hundschell et al , 2020Jakob et al 2012bJakob et al , 2013Ua-Arak et al 2016, 2017b. Moreover, the production pH during batch fermentation is crucial for the size distributions of these levans (Hundschell et al 2020;Ua-Arak et al 2017a) as also shown in the present work (Figs.…”

Section: Discussionsupporting

confidence: 83%

“…Data are exemplarily shown for the cell culture OD (600 nm) = 2.77 of G. albidus TMW 2.1191 and were highly similar for OD 2.63 and 3.0 (data not shown), respectively in the acidic environment could thus be assumed for the levansucrase of G. albidus TMW 2.1191. In contrast to the overall glucose release and produced levan amounts, the levan sizes, which are decisive for the macromolecular properties of levan (Hundschell et al 2019;Jakob et al 2013), were influenced by the production pH ( Figs. 4 ?…”

Section: Discussionmentioning

confidence: 99%

“…or Bacillus subtilis (Natto) (Fels et al 2018;Jakob et al 2012a;Korakli et al 2003;Semjonovs et al 2016;Shih et al 2005;Xu et al 2006). The macromolecular or rather hydrocolloid properties of levan in aqueous solution mainly depend on its molecular weight and can be additionally influenced by its branching degree (at position O1) and polydispersity (Hundschell et al 2019(Hundschell et al , 2020Jakob et al 2012bJakob et al , 2013. However, it is unknown, which and if a certain amount, specific size and composition of levan is essential for survival or assertiveness of the producer strains.…”

Section: Introductionmentioning

confidence: 99%

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Insights into the pH-dependent, extracellular sucrose utilization and concomitant levan formation by Gluconobacter albidus TMW 2.1191

Jakob

Gebrande

Bichler

et al. 2020

Antonie van Leeuwenhoek

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Many bacteria and archaea produce the polydisperse fructose polymer levan from sucrose upon biofilm formation via extracellular levansucrases (EC 2.4.1.10). We have investigated levansucraserelease and -activities as well as molecular size of the levan formed by the acetic acid bacterium Gluconobacter albidus TMW 2.1191 at varying environmental pH conditions to obtain insight in the ecological role of its constitutively expressed levansucrase and the produced levan. A buffer system was established enabling the recovery of levansucrasecontaining supernatants from preincubated cell suspensions at pH 4.3-pH 5.7. The enzyme solutions were used to produce levans at different pH values and sucrose concentrations. Finally, the amounts and size distributions of the produced levans as well as the corresponding levansucrase activities were determined and correlated with each other. The data revealed that the levansucrase was released into the environment independently of its substrate sucrose, and that more levansucrase was released at pH C 5.0.The glucose release and formation of high molecular weight levans ([ 3.5 kDa) from 0.1 M initial sucrose was comparable between pH * 4.3-5.7 using equal amounts of released levansucrase. Hence, this type of levansucrase appears to be structurally adapted to changes in the extracellular pH and to exhibit a similar total activity over a wide acidic pH range, while it produced higher amounts of larger levan molecules at higher production pH and sucrose concentrations. These findings indicate the physiological adaptation of G. albidus TMW 2.1191 to efficient colonisation of sucrose-rich habitats via released levansucrases despite changing extracellular pH conditions in course of acid formation.

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Section: Discussionsupporting

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Insights into the pH-dependent, extracellular sucrose utilization and concomitant levan formation by Gluconobacter albidus TMW 2.1191

Jakob

Gebrande

Bichler

et al. 2020

Antonie van Leeuwenhoek

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“…A second model, which might explain the size-dependent rheological behavior of levan, is based on the secondary structure of levan in aqueous solution. With increasing molecular weight, levan transforms from a random coil into a compact spherical molecule, which is increasingly compact/densely packed and turbidity-forming [17,41]. Therefore, Jakob et al [17] suggested that levan above a certain molecular weight might have the properties of a nanogel particle.…”

Section: Discussionmentioning

confidence: 99%

Size-Dependent Variability in Flow and Viscoelastic Behavior of Levan Produced by Gluconobacter albidus TMW 2.1191

Hundschell

Braun

Wefers

et al. 2020

Foods

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Levan is a fructan-type exopolysaccharide which is produced by many microbes from sucrose via extracellular levansucrases. The hydrocolloid properties of levan depend on its molecular weight, while it is unknown why and to what extent levan is functionally diverse depending on its size. The aim of our study was to gain deeper insight into the size-dependent functional variability of levan. For this purpose, levans of different sizes were produced using the water kefir isolate Gluconobacter albidus TMW 2.1191 and subsequently rheologically characterized. Three levan types could be identified, which are similarly branched, but differ significantly in their molecular size and rheological properties. The smallest levan (<107 Da), produced without adjustment of the pH, exhibited Newton-like flow behavior up to a specific concentration of 25% (w/v). By contrast, larger levans (>108 Da) produced at pH ≥ 4.5 were shear-thinning, and the levan produced at pH 5.0 showed a gel-like behavior at 5% (w/v). A third (intermediate) levan variant was obtained through production in buffers at pH 4.0 and exhibited the properties of a viscoelastic fluid up to concentrations of 15% (w/v). Our study reveals that the rheological properties of levan are determined by its size and polydispersity, rather than by the amount of levan used or the structural composition.

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“…A second model, which might explain the size-dependent rheological behavior of levan, is based on the secondary structure of levan in aqueous solution. With increasing molecular weight levan transforms from a random coil to a compact spherical molecule, which is increasingly compact/densely packed and turbidity forming [16,34]. Therefore, Jakob et al [16] suggested that levan above a certain molecular weight might have the properties of a nanogel particle.…”

Section: Discussionmentioning

confidence: 99%

Size-Dependent Rheological Variability of Levan Produced by Gluconobacter Albidus TMW 2.1191

Hundschell¹,

Braun²,

Wefers³

et al. 2020

Preprint

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Levan is a fructan-type exopolysaccharide, which is produced by many microbes from sucrose via extracellular levansucrases. The hydrocolloid properties of levan depend on its molecular weight, while it is unknown why and to which extent levan is functionally diverse in dependence of its size. The aim of our study was to get deeper insights into the size-dependent, functional variability of levan. For this purpose, levans of different sizes were produced using the water kefir isolate Gluconobacter albidus TMW 2.1191 and subsequently rheologically characterized. Three levan types could be identified, which are similarly branched, but significantly differ in their molecular size and rheological properties among each other. The smallest levan (< 107 Da) produced without adjustment of the pH exhibited Newton-like flow behavior up to a specific concentration of 25% (w/v). On the contrary, larger levans (> 108 Da) produced at pH ≥ 4.5 were shear-thinning and showed a gel like behavior at ≥ 5% (w/v). A third (intermediate) levan variant was obtained via production in buffers at pH 4.0 and exhibited the properties of a viscoelastic fluid at ≥ 5% (w/v). Our study reveals that the variable size and composition of levan are controllable and more decisive for its functionality than the amount of exerted levan.

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Molecular weight dependent structure of the exopolysaccharide levan

Cited by 26 publications

References 53 publications

Insights into the pH-dependent, extracellular sucrose utilization and concomitant levan formation by Gluconobacter albidus TMW 2.1191

Insights into the pH-dependent, extracellular sucrose utilization and concomitant levan formation by Gluconobacter albidus TMW 2.1191

Size-Dependent Variability in Flow and Viscoelastic Behavior of Levan Produced by Gluconobacter albidus TMW 2.1191

Size-Dependent Rheological Variability of Levan Produced by Gluconobacter Albidus TMW 2.1191

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