Characterization of Pediococcus ethanolidurans CUPV141: A β-D-glucan- and Heteropolysaccharide-Producing Bacterium.

María G Llamas-Arriba,María T Dueñas,Paloma López,Adrián Pérez-Ramos,Ana I Puertas,Alicia Prieto

doi:10.3389/fmicb.2018.02041

María G Llamas-Arriba, María T Dueñas + Show 4 more

Open Access

https://doi.org/10.3389/fmicb.2018.02041

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Abstract

Pediococcus ethanolidurans CUPV141 is an exopolysaccharide (EPS)-producing lactic acid bacterium, first isolated from Basque Country cider (Spain). Physicochemical analysis of the EPS synthesized by the bacterium revealed that CUPV141 produces mostly a homopolysaccharide (HoPS), characterized as a 2-substituted (1,3)-β-D-glucan, together with a small quantity of a heteropolysaccharide (HePS) composed of glucose, galactose, glucosamine, and glycerol-3-phosphate, this being the first Pediococcus strain described to produce this kind of polymer. On the contrary, an isogenic strain CUPV141NR, generated by chemical mutagenesis of CUPV141, produced the HePS as the main extracellular polysaccharide and a barely detectable amount of 2-substituted (1,3)-β-D-glucan. This HoPS is synthesized by the transmembrane GTF glycosyltransferase (GTF), encoded by the gtf gene, which has been previously reported to be located in the pPP2 plasmid of the Pediococcus parvulus 2.6 strain. Southern blot hybridization revealed that in CUPV141 the gtf gene is located in a plasmid designated as pPE3, whose molecular mass (34.4 kbp) is different from that of pPP2 (24.5 kbp). Analysis of the influence of the EPS on the ability of the producing bacteria to adhere to the eukaryotic Caco-2 cells revealed higher affinity for the human enterocytes of CUPV141NR compared to that of CUPV141. This result indicates that, in contrast to the 2.6 strain, the presence of the HoPS does not potentiate the binding ability of P. ethanolidurans. Moreover, it supports that the phosphate-containing bacterial HePS improved the interaction between P. ethanolidurans and the eukaryotic cells.

Highlights

Some lactic acid bacteria (LAB) produce exopolysaccharides (EPS), extracellular polymers that may remain tightly attached to the bacteria, constituting a capsule, or may be released to the environment (De Vuyst et al, 2001)
The GTF is encoded by the gtf gene, which is generally present in plasmids (Lonvaud-Funel et al, 1993; Werning et al, 2006), a chromosomal location has been observed in O. oeni (Werning et al, 2006; Dols-Lafargue et al, 2008)
A specific enzyme-linked immunosorbent assay (ELISA) method developed in our group (Werning et al, 2014) was used to test and quantify the production of the 2-substituted (1,3)-β-D-glucan by P. ethanolidurans CUPV141 cultures (OD600 nm = 1.0), which amounted to 59.8 ± 4.8 mg/L

Summary

Introduction

Some lactic acid bacteria (LAB) produce exopolysaccharides (EPS), extracellular polymers that may remain tightly attached to the bacteria, constituting a capsule, or may be released to the environment (De Vuyst et al, 2001). The most common EPS produced by strains belonging to this genus is a 2-substituted (1,3)-β-D-glucan (β-D-glucan) (Llaubères et al, 1990; Dueñas-Chasco et al, 1997) synthesized by the GTF glycosyltransferase (GTF) (Werning et al, 2008, 2014) This HoPS is produced by LAB isolated from alcoholic beverages: Pediococcus damnosus or Oenococcus oeni strains in wines (Lonvaud-Funel and Joyeux, 1988; Dols-Lafargue et al, 2008), Lactobacillus and Pediococcus strains in ciders (Dueñas et al, 1995; Fernández et al, 1995; Ibarburu et al, 2007; Garai-Ibabe et al, 2010a; Puertas et al, 2018) and Lactobacillus strains in beers (Fraunhofer et al, 2018). The GTF is encoded by the gtf gene, which is generally present in plasmids (Lonvaud-Funel et al, 1993; Werning et al, 2006), a chromosomal location has been observed in O. oeni (Werning et al, 2006; Dols-Lafargue et al, 2008)

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