Dextran production by Lactobacillus sakei MN1 coincides with reduced autoagglutination, biofilm formation and epithelial cell adhesion

Abstract

In this work we have investigated two dextran-producing lactic acid bacteria, Lactobacillus sakei MN1 and Leuconostoc mesenteroides RTF10, isolated from fermented meat products. These bacteria synthesise dextran when sucrose, but not glucose, is present in the growth medium. The influence of dextran on bacterial aggregation, adhesion and biofilm formation was investigated in cultures challenged with sucrose or glucose. For Lb. sakei MN1, the synthesis of the dextran drastically impaired the three processes; in contrast it had no effect on Lc. mesenteroides RTF10. Therefore, the influence of dextran on probiotic properties of Lb. sakei MN1 was tested in vivo using gnotobiotic zebrafish models. The bacterium efficiently colonised the fish gut and inhibited the killing activity of Vibrio anguillarum NB10[pOT11]. Furthermore, under conditions of dextran synthesis, the adhesion of Lb. sakei MN1 to the epithelial cells decreased, without greatly affecting its anti V. anguillarum activity.

Rheology and bioactivity of high molecular weight dextrans synthesised by lactic acid bacteria

“…Samples were examined using a JEOL 1230 microscope operated at 100 kV at the Electron Microscopy service of Centro de Investigaciones Biológicas (CIB, Madrid, Spain). and grown as monolayers of differentiated and polarised cells for 21 days as previously described (Nácher-Vázquez et al, 2017). Cell concentrations were determined as previously described (Garai-Ibabe et al, 2010).…”

“…0.1 mL of bacterial suspension was added per well (ratio 10:1, bacteria:Caco-2 cells) and the plates were incubated for 1 h at 37 ºC. Then, un-adhered bacteria were removed and, the cellassociated bacteria quantified after platting onto MRSG plates, as previously described (Nácher-Vázquez et al, 2017). All adhesion assays were conducted in triplicate.…”

“…mesenteroides RTF10 and Lb. sakei MN1 isolated from Spanish fermented meat (Notararigo et al, 2013;Nácher-Vázquez et al, 2015;Nácher-Vázquez et al, 2017). LAB were grown in CDM defined medium instead of a rich medium in order to avoid, or diminish, the co-precipitation of interfering compounds during EPS quantification and further purification (Montersino, Prieto, Muñoz, & Rivas, 2008;Notararigo et al, 2013).…”

“…2S). Previous TEM analysis of meat LAB colonies, allowed us to detect the dextran surrounding cells grown in MRSS and not in MRSG (Nácher-Vázquez et al, 2017). Thus, in order to determine the dextran location at cellular level, Algerian LAB colonies were analysed by TEM.…”

Structural analysis and characterization of a clinically important low molecular weight natural dextran synthesized by Leuconostoc lactis KU665298 dextransucrase

“…Dextran is an example of bacterial homopolysaccharide composed of D-glucose and largely of -1,6-glucopyranosidic linkages in the main chain (Naessens et al, 2005;Vettori et al, 2012;Liu et al, 2017;Nacher-Vazquez et al, 2017). Lactic acid bacteria have a long history of safe use in human consumption and, therefore, among variety of microorganisms, are most widely explored for the production of microbial exopolysaccharides (Nikolic et al, 2012).…”