New Insight into Biofilm Formation Ability, the Presence of Virulence Genes and Probiotic Potential of Enterococcus sp. Dairy Isolates

Abstract

Enterococci have controversial status due to their emerging role in nosocomial infections and transmission of antibiotic resistance genes, while some enterococci strains are used as probiotics for humans and animals and starter cultures in dairy industry. In order to improve our understanding of factors involved in the safe use of enterococci as potential probiotics, the antibiotic susceptibility, virulence and probiotic traits of 75 dairy enterococci isolates belonging to Enterococcus durans (50), En. faecium (15), En. faecalis (6), En. italicus (3), and En. hirae (1) were evaluated. The results revealed that ciprofloxacin resistance and biofilm formation are correlated with isolates originated from Golija mountain (Serbia), while gelatinase activity was more common in isolates from Prigorje region (Croatia), pointing to uncontrolled use of antibiotics and anthropogenic impact on dairy products' microbiota in these regions. The virulence genes were sporadically present in 13 selected dairy enterococci isolates. Interestingly, biofilm formation was correlated with higher ability of strains to reduce the adhesion of E. coli and Salmonella Enteritidis to HT29-MTX cells. To our knowledge this is the first study reporting the presence of the esp gene (previously correlated with pathogenesis) in dairy enterococci isolates, mostly associated with the genes involved in adhesion property. Hence, the results of this study revealed that the virulence genes are sporadically present in dairy isolates and more correlated to adhesion properties and biofilm formation, implicating their role in gut colonization rather than to the virulence traits.

Safety and Growth Optimization of Lactic Acid Bacteria Isolated From Feedlot Cattle for Probiotic Formula Design

“…On the contrary, a lack of amplification of the virulence genes here assayed was reported for E. durans and E. hirae from fermented sausages and pet feces ( Martin et al, 2005 ; Fontana et al, 2009 ; Iseppi et al, 2015 ). In particular, fsrA gene coding for quorum sensing regulatory mechanism was present in feedlot E. hirae CRL2068 in coincidence with that recently described for dairy strains by Popović et al (2018) . The lack of amplification of fsrA gene in E. durans feedlot strains agrees with that reported for this species by Golińska et al (2013) .…”

Hydrophobic and adhesive patterns of lactic acid bacteria and their antagonism against foodborne pathogens on tomato surface (Solanum lycopersicumL.)

“…Cell wall–associated extracellular surface proteins encoded by the gene esp that promotes adhesion, colonization and contributes to biofilm formation have been also reported in dairy enterococci isolates (Popović et al . 2018).…”

Lactobacillus fermentum strains from rice water and lemon pickle with potential probiotic properties and wastewater treatment applications

“…The absence of gelatinase, metalloproteinases (MMPs) secreted by pathogenic bacteria, provided evidence to the non-virulent nature of the strains under investigation which increases their modulation to be employed in waste water treatment as they are not imparting virulence genes to sewage (Sharma, Sharma and Sharma 2017). Further con rmations should be done to rule out the absence of the virulence factors as per (Popovic et al 2018). RS based partially puri ed bacteriocins showed potent antagonistic activity against the target pathogens while, T1 the observations were not much fruitful.…”