Comparative study of physicochemical properties of dextran and reuteran synthesised by two glucansucrases that are highly similar in amino acid sequence

Abstract

Recently, lactic acid bacteria (LAB)-derived a-glucans have drawn strong attention owing to their various structural organisation and wide (potential) applications in the medicine, food, cosmetic, and biotechnology industries. However, the physicochemical properties of diverse a-glucans, particularly reuteran, remain largely unknown, which significantly impedes their wider applications. This study comparatively evaluated the physicochemical properties of two different a-glucans, Gtf-DSM dextran, and GtfO reuteran produced by the dextransucrase Gtf-DSM from Lactobacillus ingluviei DSM 14792 and the reuteransucrase GtfO from Lactobacillus reuteri ATCC 55730, which are two glucansucrases highly similar in amino acid sequence. The surface morphology analysis demonstrated that Gtf-DSM dextran had a holey and fissured microstructure; however, GtfO reuteran had an irregular dendritic microstructure, forming a fibrous network. Compared to GtfO reuteran, Gtf-DSM dextran showed a larger average particle diameter (162.4 versus 90.3 nm). Additionally, Gtf-DSM dextran displayed some prominent properties, such as better thermostability, higher apparent viscosity, and stronger gel-forming capability, than GtfO reuteran. These results provide a theoretical basis for stimulating the applications of LAB-derived a-glucans in various fields.

Glucansucrase Produced by Lactic Acid Bacteria: Structure, Properties, and Applications

“…[137]. Among them, TGA can analyze the weight-related quantity (such as mass, solid residue, or residual rate) of the sample as a function of temperature or time so as to obtain the thermal stability of the EPS, its thermal decomposition, its impurity composition, its thermal decomposition products, and other information [138]. DSC can analyze the pyrolysis mode and thermal stability of EPS.…”

Mutations in the Different Residues between Dextransucrase Gtf-DSM and Reuteransucrase GtfO for the Investigation of Linkage Specificity Determinants

“…Two wild-type recombinant plasmids carrying the N-terminally truncated and C-terminally His-tagged L. ingluviei DSM 14792 Gtf-DSM and L. reuteri ATCC 55730 GtfO encoding genes, respectively, were constructed in our previous work. 23,25 These two wild-type plasmids were used as original templates for sitedirected mutagenesis. The chemicals used for cell culture and protein expression, including peptone, yeast extract, isopropyl β-D-1thiogalactopyranoside (IPTG), and ampicillin sodium, were obtained from Sigma or Sinopharm Chemical Reagent.…”