Characterization and antibacterial activity of a novel exopolysaccharide produced by Lactobacillus kefiranofaciens DN1 isolated from kefir

Antimicrobial and anti-biofilm activities of Lactobacillus kefiranofaciens DD2 against oral pathogens

“…The commercial strains and those isolated from kefir were all highly resistant to α-amylase activity, which may be due to the action of capsular materials or protective polymeric substances surrounding the cell [18]. …”

“…Indeed, strains that lowered the supernatant pH by a larger margin showed greater inhibition of both S. mutans and S. sobrinus . Notably, the culture supernatant of L. kefiranofaciens DD2 exhibited antimicrobial activity despite a relatively high pH as compared to the commercial strains, implying that other substances contribute to the inhibitory effects [18,29]. Indeed, in our previous study, we found that L. kefiranofaciens produces an antimicrobial exopolysaccharide [18], which could be linked to the antimicrobial action; however, additional studies are needed to investigate the mechanism of action.…”

“…Partial sequences of the 16S ribosomal RNA gene were amplified from the genomic DNA of the strains and sequenced according to the protocol described in our previous study [18]. Briefly, genomic DNA extraction from the isolates was performed using the NucliSENS easyMAG instrument (bioMérieux, Marcy l’Etoile, France) according to the manufacturer’s instructions.…”

“…Indeed, kefir contains over 50 species of LAB, yeasts, and acetic acid bacteria as well as their metabolites such as lactic acid, exopolysaccharides, and peptides that confer various beneficial health effects [2,16–18]. Lactobacillus kefiranofaciens is a typical probiotic microorganism found in kefir [4], and we previously demonstrated its antimicrobial effects against pathogenic bacteria in vitro and its ability to improve the balance of intestinal microbiota by reducing the proportion of opportunistic pathogens [4,18]. However, no study has investigated the inhibitory effect of kefir isolates against oral pathogens and the associated mechanisms.…”

Kefir micro-organisms: their role in grain assembly and health properties of fermented milk

“…However, none of them produced fractions of a molecular weight higher than 10 5 Da. Jeong et al (2017) demonstrated that L. kefiranofaciens DN1 produces a different EPS from kefiran composed of mannose, arabinose, glucose, galactose and rhamnose when it grow in glucose. Otherwise, L. kefiranofaciens 1P3 isolated from Brazil kefir grains was able to produce an a-glucan in the presence of sucrose; however, they did not report if the same strains is able to produce EPS from lactose (de Paiva et al 2016).…”