Use of Potential Probiotic Lactic Acid Bacteria (LAB) Biofilms for the Control of Listeria monocytogenes, Salmonella Typhimurium, and Escherichia coli O157:H7 Biofilms Formation

Abstract

Use of probiotic biofilms can be an alternative approach for reducing the formation of pathogenic biofilms in food industries. The aims of this study were (i) to evaluate the probiotic properties of bacteriocinogenic (Lactococcus lactis VB69, L. lactis VB94, Lactobacillus sakei MBSa1, and Lactobacillus curvatus MBSa3) and non-bacteriocinogenic (L. lactis 368, Lactobacillus helveticus 354, Lactobacillus casei 40, and Weissela viridescens 113) lactic acid bacteria (LAB) isolated from Brazilian’s foods and (ii) to develop protective biofilms with these strains and test them for exclusion of Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Typhimurium. LAB were tested for survival in acid and bile salt conditions, surface properties, biosurfactant production, β-galactosidase and gelatinase activity, antibiotic resistance and presence of virulence genes. Most strains survived exposure to pH 2 and 4% bile salts. The highest percentages of auto-aggregation were obtained after 24 h of incubation. Sixty-seven percentage auto-aggregation value was observed in W. viridescens 113 and Lactobacillus curvatus MBSa3 exhibited the highest co-aggregation (69% with Listeria monocytogenes and 74.6% with E. coli O157:H7), while the lowest co-aggregation was exhibited by W. viridescens 113 (53.4% with Listeria monocytogenes and 38% with E. coli O157:H7). Tests for hemolytic activity, bacterial cell adherence with xylene, and drop collapse confirmed the biosurfactant-producing ability of most strains. Only one strain (L. lactis 368) produced β-galactosidase. All strains were negative for virulence genes cob, ccf, cylLL, cylLs, cyllM, cylB, cylA and efaAfs and gelatinase production. The antibiotic susceptibility tests indicated that the MIC for ciprofloxacin, clindamycin, gentamicin, kanamycin, and streptomycin did not exceed the epidemiological cut-off suggested by the European Food Safety Authority. Some strains were resistant to one or more antibiotics and resistance to antibiotics was species and strain dependent. In the protective biofilm assays, strains L. lactis 368 (bac-), Lactobacillus curvatus MBSa3 (bac+), and Lactobacillus sakei MBSa1 (bac+) resulted in more than six log reductions in the pathogens counts when compared to the controls. This effect could not be attributed to bacteriocin production. These results suggest that these potential probiotic strains can be used as alternatives for control of biofilm formation by pathogenic bacteria in the food industry, without conferring a risk to the consumers.

Listeria monocytogenes’in Gelişimi Üzerine Probiyotik Biyofilmlerin İnaktivasyon Etkisi

“…For this experiment, 0.1% L. monocytogenes, 0.5% L. monocytogenes, and 0.1% mix of L. monocytogenes and probiotic culture (0.1% L. rhamnosus or 0.1% L. casei Shirota) were added onto probiotic biofilm and reduction .01 log cfu/mL whereas the reduction in L. monocytogenes attached to biofilm changed between 0.40 and 1.69 log cfu/mL. These findings proved the hypothesis of Gomez et al [4] that planktonic cells of L. monocytogenes were more susceptible than biofilm of L. monocytogenes. Similarly, Guerrierri et al [11] determined that L. plantarum 35d biofilm, L. plantarum 396/1 biofilm and Enterococcus casseliflavus IM 416K1 biofilm caused more reduction in planktonic cells of L. monocytogenes than adherent cells of L. monocytogenes.…”

“…Several fermented food products contain lactic acid bacteria with probiotic properties and are accepted as safe due to protective role of probiotics [4] . Probiotic bacteria produce antimicrobial compounds against various pathogens and thus might form a natural barrier against pathogen in the gastrointestinal tract or preserve food [5] .…”

“…In several studies it was reported that adherence of lactic acid bacteria to the surface may prevent the adherence and the biofilm formation of L. monocytogenes. The use of probiotic biofilms can be considered as an alternative approach for reducing growth of pathogenic bacteria as regards human health and food safety [4] . However, the optimal functionality and expression of health-promoting physiological functions of probiotics is dependent on survivability and colonization in gastrointestinal tract and fermented foods [20] .…”

Antibiofilm and Antiadhesive Activities of Different Synbiotics

“…Gómez et al used preformed probiotic biofilms (including L. lactis and L. casei) as alternative approach to contrast the formation of pathogenic biofilms (L. monocytogenes, E. coli O157:H7 and Salmonella typhimurium) in food industries [38].…”

The Use of Starter Cultures in Traditional Meat Products

“…LAB biofilms may be used to control the formation of biofilms by the foodborne pathogens Listeria monocytogenes, Salmonella Typhimurium, and Escherichia coli O157:H7 [143].…”