Analysis of Structural and Functional Differences of Glucans Produced by the Natively Released Dextransucrase of Liquorilactobacillus hordei TMW 1.1822

Abstract

The properties of the glucopolymer dextran are versatile and linked to its molecular size, structure, branching, and secondary structure. However, suited strategies to control and exploit the variable structures of dextrans are scarce. The aim of this study was to delineate structural and functional differences of dextrans, which were produced in buffers at different conditions using the native dextransucrase released by Liquorilactobacillus (L.) hordei TMW 1.1822. Rheological measurements revealed that dextran produced at pH 4.0 (M W = 1.1 * 10 8 Da) exhibited the properties of a viscoelastic fluid up to concentrations of 10% (w/v). By contrast, dextran produced at pH 5.5 (M W = 1.86 * 10 8 Da) was gel-forming already at 7.5% (w/v). As both dextrans exhibited comparable molecular structures, the molecular weight primarily influenced their rheological properties. The addition of maltose to the production assays caused the formation of the trisaccharide panose instead of dextran. Moreover, pre-cultures of L. hordei TMW 1.1822 grown without sucrose were substantial for recovery of higher dextran yields, since the cells stored the constitutively expressed dextransucrase intracellularly, until sucrose became available. These findings can be exploited for the controlled recovery of functionally diverse dextrans and oligosaccharides by the use of one dextransucrase type.

Water kefir: Factors affecting grain growth and health-promoting properties of the fermented beverage

“…Liquorilactobacillus hordei present in the water kefir grain consortium produces a high-molecular-weight dextran from sucrose . This dextran induces S. cerevisiae aggregation, conforming the first step in grain formation (Xu et al, 2018) and has the ability to form gels at concentrations higher than 7.5% (w/v) (Schmid et al, 2021). Liquorilactobacillus hordei possesses an extracellular dextransucrase that produces O3branched α 1-6 linked glucose polymers from sucrose and its activity depends on the pH, decreasing at pH below 3.5 (Bechtner, Wefers, et al, 2019;Schmid et al, 2019).…”

Variability of Bacterial Homopolysaccharide Production and Properties during Food Processing

“…The shorter the linear chain, the lower the viscosity [ 19 , 20 ]. Other factors, such as pH, the presence of maltose or temperature, play a role in the structure and size of the produced HoPS dextran [ 37 , 38 , 39 ].…”