Background: Raw milk, meat and plant materials are subjected to high risks of contamination by various pathogenic bacteria and thus their growth prevention is a great challenge in the food industry. Food fermentation by lactic acid bacteria (LAB) besides changing its organoleptic characteristics also helps to eliminate unfavorable microflora and represses growth of pathogens. To the date only few LABs has been reported to exhibit activity against bacteria embedded in the biofilms characterized by extreme resistance to antimicrobials, high exchange rate with resistance genes and represent high risk factor for foodborne disease development. Results: Six novel LAB strains isolated from the clover silage exhibited pronounced antibacterial activity against biofilm embedded pathogens. We show explicitly that these strains demonstrate high acidification rate, completely repress the growth of E. coli, S. aureus and to a lesser extent P. aeruginosa as well as exhibit appropriate probiotic and milk-fermenting properties. Moreover, in contrast to the approved probiotic strain Lactobacillus plantarum 8PA3, the new isolates were able to efficiently eradicate preformed biofilms of these pathogens and prevent bacterial spreading originating from the biofilm. We suggest these strains as potential additives to the pre-cultures of conventional LAB strains as efficient tools targeting foodborne pathogens in order to prevent food contamination from either seeded raw material or biofilm-fouled equipment. Conclusions: The AG10 strain identified as L. plantarum demonstrate attractive probiotic and milk fermentation properties as well as high resistance to simulated gastric conditions thus appearing perspective as a starter culture for the prevention of bacterial contamination originating from fouled equipment during milk fermentation.

A positive effect of flaxseed mucilage (FSM) addition (at concentrations of 0.1, 0.2, and 0.4%) to MRS and milk whey nutrient medium on the survival, auto-aggregation, hydrophobicity, adhesive, and antioxidant properties of L. bulgaricus, L. fermentum AG8, and L. plantarum AG9 was shown. It was found that the AG 8 strain became less sensitive to 7% NaCl concentrations (the cell survival rate in the experiment with 0.4% flaxseed mucilage increased by 10% compared to the control). Cultivation in the presence of FSM led to an increase in auto-aggregation, especially in the case of AG8 (from 60 to 85%) and AG9 (from 50 to 80%) strains, and an increase in hydrophobicity was seen: for L. fermentum AG8, it was from 30% to 62–72%, for L. fermentum AG9 from 30% to 35–42%, and for L. bulgaricus from 20% to 30%. The adhesive properties of the L. fermentum AG8 and L. plantarum AG9 cells increased from 0.472 to 1 nN (nanonewton) and from 0.630 to 2.5 nN, respectively. The presence of flaxseed mucilage increased the total phenolic content in cell-free supernatants after 48 h of cultivation. The concentration of 0.1–0.2% FSM increased the OH-scavenging activity of milk whey nutrient medium cell-free supernatants of strains AG8 and AG9 by 7–10%. Flaxseed mucilage can serve as a promising bioactive additive that elevates antioxidant activity, increases the resistance and survival of Lactobacillus cells in the gastrointestinal tract, and leads to the synthesis of lipase and α-glucosidase inhibitors. The co-culture of these lactic acid bacteria in the presence of FSM and milk components in the form of whey leads to the synthesis of lipase and α-glucosidase inhibitors more than the culturing on de Man, Rogosa, and Sharpe broth.