The function of lactic acid bacteria and brine solutions on biogenic amine formation by foodborne pathogens in trout fillets

The influences of lactic acid bacteria and brine solutions on the biogenic amine formation by Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Enterococus faecalis, Pseudomonas aeruginosa, Listeria monocytogenes, Aeromonas hydrophila and Salmonella paratyphi A in fermented trout fillets were investigated. Fish fillets were divided into four groups, group 1 without any lactic acid bacteria inoculation, group 2 and group 3 with different salt concentration inoculated with lactic acid bacteria and food-borne pathogens, and group 4 inoculated with lactic acid bacteria and food-borne pathogens without a salt solution. The histamine content in trout fillets in group 4 was found to be more than 10 mg/100 g, while the other groups contained less than 7.5 mg/100 g. The highest tyramine production was found for group 1 and group 3, ranging from 3 to 18 mg/100 g. Lactic acid bacteria did not seem to play an important role on biogenic amine production by food borne pathogens, while adding brine solution on fillets has inhibitory effects on some of the biogenic amines.     

Interaction between lactic acid bacteria and food‐borne pathogens on putrescine production in ornithine‐enriched broth

Interactions of mixed cultures [lactic acid bacteria (LAB) and food‐borne pathogens (FBP)] on putrescine (PUT) as well as other biogenic amines (BAs) production were investigated in ornithine‐enriched broth. Significant differences in BAs production were found among the bacterial strains (P < 0.05). Conversion of ornithine into PUT by Salmonella Paratyphi A and Aeromonas hydrophila as well as Listeria monocytogenes and Staphylococcus aureus was high (>75 mg L^?1), whereas other bacterial strains yielded below 50 mg L^?1 of PUT. LAB strains resulted in significant reduction in PUT by Pseudomonas aeruginosa and Enterobacteriaceae, except for Escherichia coli, which was stimulated more than two‐fold PUT in the presence of Lactococcus lactis subsp. lactis. Lactobacillus plantarum had generally inhibition effect on histamine (HIS) and tyramine production by FBP, whereas Lc. lactic subsp. lactic slightly stimulated HIS by E. coli and A. hydrophila. Streptococcus thermophilus resulted in 1.5‐fold higher HIS formation by bacteria (10 mg L^?1). Consequently, the interaction between LAB and specific FBP might result in significant inhibition of amine accumulation, if the correct LAB strains are used.     

Production of biogenic amines by lactic acid bacteria and bifidobacteria isolated from dairy products and beer

The aim was to monitor production of eight biogenic amines (BAs) (histamine, tyramine (TYR), tryptamine, putrescine, cadaverine (CAD), phenylethylamine, spermine and spermidine) by selected 81 lactic acid bacteria (LAB) strains: Lactobacillus, Lactococcus, Leuconostoc, Enterococcus, Pediococcus, Tetragenococcus and Bifidobacterium. The tested LAB and bifidobacteria were isolated from dairy products and beer. The decarboxylase activity of the micro‐organisms was studied in growth medium after cultivation. The activity was monitored by HPLC after the pre‐column derivatisation with dansylchloride. Fifty LAB showed decarboxylase activity. Thirty‐one strains produced low concentrations of CAD (≤10 mg L^?1). Almost 70% of beer isolates generated higher amounts of TYR (≤3000 mg L^?1). Most of the tested LAB demonstrated decarboxylase activity. The above micro‐organisms can contribute to the increase of content of BAs in dairy products or beer and thereby threaten food safety and health of consumers. Production of BAs even by the representatives of some probiotic strains (Bifidobacterium and Lactobacillus rhamnosus) was detected in this research. This study has also proved that contaminating LAB can act as sources of higher amounts of CAD and TYR in beer.     

Selected lactic acid bacteria as a hurdle to the microbial spoilage of cheese: Application on a traditional raw ewes' milk cheese

To evaluate the efficacy of lactic acid bacteria (LAB) to improve the hygienic safety of a traditional raw milk cheese, the raw ewes' milk protected denomination of origin (PDO) Pecorino Siciliano cheese was used as a model system. Different Pecorino Siciliano curds and cheeses were used as sources of autochthonous LAB subsequently used as starter and non-starter LAB. These were screened for their acidification capacity and autolysis. Starter LAB showing the best performance were genotypically differentiated and identified: two strains of Lactococcus lactis subsp. lactis were selected. From the non-starter LAB, Enterococcus faecalis, Lactococcus garvieae and Streptococcus macedonicus strains were selected. The five cultures were used in individual or dual inocula to produce experimental cheeses in a dairy factory for which production was characterised by high numbers of undesirable bacteria. At 5-month of ripening, the experimental cheeses produced with LAB were characterised by undetectable levels of enterobacteria and pseudomonads and the typical sensory attributes.     

Effects of specific lactic acid bacteria species on biogenic amine production by foodborne pathogen

The influences of lactic acid bacteria (LAB) on biogenic amines formation by foodborne pathogens (FBP) were investigated. Biogenic amines production by single and mix cultures was tested in histidine decarboxylase broth. All of the mix cultures (LAB with FBP) inhibited significantly (P < 0.05) the ammonia accumulation except for Escherichia coli with Lactococcus lactic subsp. lactic and Lactobacillus plantarum. Although LAB with most of the pathogen showed considerably stimulation effects on putrescine, cadaverine, spermine, 2‐phenylethylamine, histamine (HIS), tyramine, trimethylamine, dopamine and agmatine (AGM), some of the LAB with pathogens showed poor inhibition effect on different amines formation. HIS production by Klebiella pneumonia was 0.16 mg L^?1, whereas HIS value in presence of Lb. plantarum increased to 30.92 mg L^?1. Consequently, LAB inhibition of the ammonium production by FBP is favourable, while the stimulation effects of LAB on biogenic amines formation by FBPs are not desirable for food industry.     

Survival of probiotic adjunct cultures in cheese and challenges in their enumeration using selective media

Various selective media for enumerating probiotic and cheese cultures were screened, with 6 media then used to study survival of probiotic bacteria in full-fat and low-fat Cheddar cheese. Commercial strains of Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus paracasei, or Bifidobacterium lactis were added as probiotic adjuncts. The selective media, designed to promote growth of certain lactic acid bacteria (LAB) over others or to differentiate between LAB, were used to detect individual LAB types during cheese storage. Commercial strains of Lactococcus, Lactobacillus, and Bifidobacterium spp. were initially screened on the 6 selective media along with nonstarter LAB (NSLAB) isolates. The microbial flora of the cheeses was analyzed during 9 mo of storage at 6°C. Many NSLAB were able to grow on media presumed selective for Lactococcus, Bifidobacterium spp., or Lb. acidophilus, which became apparent after 90 d of cheese storage, Between 90 and 120 d of storage, bacterial counts changed on media selective for Bifidobacterium spp., suggesting growth of NSLAB. Appearance of NSLAB on Lb. casei selective media [de man, Rogosa, and Sharpe (MRS) + vancomycin] occurred sooner (30 d) in low-fat cheese than in full-fat control cheeses. Differentiation between NSLAB and Lactococcus was achieved by counting after 18 to 24 h when the NSLAB colonies were only pinpoint in size. Growth of NSLAB on the various selective media during aging means that probiotic adjunct cultures added during cheesemaking can only be enumerated with confidence on selective media for up to 3 or 4 mo. After this time, growth of NSLAB obfuscates enumeration of probiotic adjuncts. When adjunct Lb. casei or Lb. paracasei cultures are added during cheesemaking, they appear to remain at high numbers for a long time (9 mo) when counted on MRS + vancomycin medium, but a reasonable probability exists that they have been overtaken by NSLAB, which also grow readily on this medium. Enumeration using multiple selective media can provide insight into whether it is the actual adjunct culture or a NSLAB strain that is being enumerated.     

Diversity and technological potential of lactic acid bacteria of wheat flours

Lactic acid bacteria (LAB) were analysed from wheat flours used in traditional bread making throughout Sicily (southern Italy). Plate counts, carried out in three different media commonly used to detect food and sourdough LAB, revealed a maximal LAB concentration of approximately 4.75 Log CFU g⁻¹. Colonies representing various morphological appearances were isolated and differentiated based on phenotypic characteristics and genetic analysis by randomly amplified polymorphic DNA (RAPD)-PCR. Fifty unique strains were identified. Analysis by 16S rRNA gene sequencing grouped the strains into 11 LAB species, which belonged to six genera: Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Pediococcus and Weissella. Weissella cibaria, Lactobacillus plantarum, Leuconostoc pseudomesenteroides and Leuconostoc citreum were the most prevalent species. The strains were not geographically related. Denaturing gradient gel electrophoresis (DGGE) analysis of total DNA of flour was used to provide a more complete understanding of the LAB population; it confirmed the presence of species identified with the culture-dependent approach, but did not reveal the presence of any additional LAB species. Finally, the technological characteristics (acidifying capacity, antimicrobial production, proteolytic activity, organic acid, and volatile organic compound generation) of the 50 LAB strains were investigated. Eleven strains were selected for future in situ applications.     

The Impact of Carvacrol on Ammonia and Biogenic Amine Production by Common Foodborne Pathogens

The impact of carvacrol at different levels (0.1%, 0.5%, and 1%) on ammonia (AMN) and biogenic amines (BAs) production by 8 common foodborne pathogens (FBPs) (Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, Pseudomonas aeruginosa, Listeria monocytogenes, Aeromonas hydrophila, and Salmonella Paratyphi A) was studied using a rapid high‐performance liquid chromatography method. Significant differences among bacteria (P < 0.05) in AMN and BA production were observed using a tyrosine decarboxylase broth. Tyramine, dopamine, agmatine, spermine, and putrescine were the main amines produced by the bacteria. Tyramine production by P. aeruginosa was the highest (967 mg/L), whereas K. pneumoniae was the poorest tyramine producer (6.42 mg/L). AMN and BA production varied significantly depending on carvacrol levels and the specific bacterial strains. Tyramine production for all bacterial strains was significantly suppressed by addition of carvacrol at levels of 0.5% and 1%, but not 0.1%. Consequently, the effect of carvacrol on BA and AMN formation by FBP was dependent on bacterial strain as well as carvacrol level.     

Evaluation of lactic acid bacteria and yeast diversity in traditional white pickled and fresh soft cheeses from the mountain regions of Serbia and lowland regions of Croatia

The goal of this study was the characterisation of indigenous lactic acid bacteria (LAB) and yeasts isolated from nine white pickled (BG) and nine fresh soft (ZG) artisanal cheeses collected in Serbia and Croatia. While LAB were present in all of the cheeses collected, yeasts were found in all BG cheeses but only in three ZG cheese samples. High LAB and yeast species diversity was determined (average H′_L = 0.4 and H′_Y = 0.8, respectively). The predominant LAB species in white pickled (BG) cheeses were Lactococcus lactis, Lactobacillus plantarum, and Leuconostoc mesenteroides, while in fresh soft (ZG) cheeses the most dominant LAB species were L. lactis, Enterococcus faecalis, and Leuconostoc pseudomesenteroides. Among the 20 yeast species found, Debaryomyces hansenii, Candida zeylanoides, and Torulaspora delbrueckii were found to be predominant in BG cheeses, while Yarrowia lipolytica was predominant in ZG cheeses. The characterisation of metabolic and technological potentials revealed that 53.4% of LAB isolates produced antimicrobial compounds, 44.3% of LAB strains showed proteolytic activity, while most of the yeast species possessed either lipolytic or proteolytic activity. In conclusion, the results obtained in this study showed that the composition of LAB and yeast populations in white pickled and fresh soft cheeses is region specific. The knowledge gained in this study could eventually be used to select region specific LAB and yeast strains for the production of white pickled and fresh soft artisanal cheeses with geographically specific origins under controlled conditions.     

Is the production of the biogenic amines tyramine and putrescine a species-level trait in enterococci?

Biogenic amines (BA) are toxic nitrogenous compounds that can be accumulated in foods via the microbial decarboxylation of certain amino acids. Lactic acid bacteria (LAB) strains belonging to different species and genera have been described as BA producers and are mainly responsible for their synthesis in fermented foods. It is generally accepted that the capacity to produced BAs is strain-dependent. However, the large number of enterococci identified as BA producers suggests that the aminogenic trait may be a species-level characteristic. Enterococcus faecalis, Enterococcus faecium and Enterococcus durans strains of different origin were analysed to determine their capacity to produce tyramine and putrescine. The presence of the genes responsible for this and the identity of their flanking regions were checked by PCR. The results suggest that tyramine biosynthesis is a species-level characteristic in E. faecalis, E. faecium and E. durans. Putrescine synthesis was found to be a species-level trait of E. faecalis, with production occurring via the agmatine deamination pathway. Some E. faecium strains of human origin also produced putrescine; this trait was probably acquired via horizontal gene transfer.     

Lactic acid bacteria isolated from a hand-made blue cheese

Nearly 500 strains isolated from different media used to study the aerobic mesophilic and lactic acid flora of Valdeón cheese (a Spanish hand-made blue cheese) have been identified. Nearly 95% of aerobic mesophiles were lactic acid bacteria (LAB). From these, Enterococcus (40·4%) and Lactococcus (42·2%) were the dominant genera, with Lactobacillus (4·1%) and Leuconostoc (5·0%) being also found. The selectivity of the other media used was variable and this is discussed. Several species of Enterococcus were isolated from our samples (Ent. avium, Ent. faecium and Ent. durans), although one was outstanding (Ent. faecalis, 24·7% of the total of strains identified). The dominating LAB species found was Lact. lactis subsp. lactis (31·1%). Other LAB identified were Lact. raffinolactis, Lb. plantarum, Lb. casei, Leuc. mesenteroides subsp. dextranicum, Leuc. mesenteroides subsp. mesenteroides and Leuc. paramesenteroides. The evolution of the lactic-acid flora found during the manufacture and ripening of this variety of cheese showed a pattern marked by the dominance of lactococci and enterococci during the first stages and the substitution of lactococci by lactobacilli and leuconostoc from drying onwards which would be, along with enterococci, the major genera found in the cheese at the stage of consumption. From a technological point of view, the quantitative importance of certain species such as Lact. lactis and Ent. faecalis, as well as the presence of others, i.e. Lb. plantarum and Leuc. mesenteroides, suggest their possible use as starters in the industrial manufacture of this variety.     

Occurrence of biogenic amine-forming lactic acid bacteria in wine and cider

A collection of 810 lactic acid bacteria (LAB) strains isolated from wine and cider was screened for potential biogenic amine (BA) producers by combining molecular and phenotypic approaches. A newly developed multiplex PCR method allowed for the simultaneous detection of four genes involved in the production of histamine (histidine decarboxylase, hdc), tyramine (tyrosine decarboxylase, tyrdc) and putrescine (via either ornithine decarboxylase, odc, or agmatine deiminase, agdi) while TLC and HPLC analysis allowed for BA-production determination. One hundred and fifty-eight LAB strains were monitored by the molecular/phenotypic double approach and revealed a good correlation between genotypic and phenotypic data. Eighteen per cent of the tested strains were positive for at least one BA target gene with up to three detected simultaneously, in particular amongst Lactobacillus brevis and Lactobacillus hilgardii isolates for the tyrdc and agdi genes. The most frequent gene corresponded to the agdi gene detected in 112 strains (14% of all LAB strains) of 10 different LAB species. The tyrdc gene was detected in 67 strains represented by 7 different LAB species (8% overall), especially those isolated from wine. Lower levels of hdc⁺ (2% of strains) and especially odc⁺ (0.5% of strains) strains were observed. Interestingly, species that have never been described to carry BA-producing pathway genes were identified in this study. Furthermore, only one cadaverine-producer was detected and corresponded to Lactobacillus 30a, a collection strain not found in fermented beverages, although cadaverine is commonly detected in wines.     

Characterization of psychrotrophic bacterial communities in modified atmosphere-packed meat with terminal restriction fragment length polymorphism

Characterization of psychrotrophic lactic acid bacteria (LAB) and Brochothrix thermosphacta communities is needed to understand the microbial ecology of spoilage of modified atmosphere-packed (MAP) meats. To overcome the limitations of the currently used methods for the characterization of psychrotrophic bacterial communities in meat, we developed a culture-independent, 16S rRNA gene-targeted terminal restriction fragment length polymorphism (T-RFLP) method. An identification library consisting of 100 Gram-positive and 30 Gram-negative meat-associated bacterial strains was set up to identify the terminal restriction fragments derived from the communities. The taxonomic resolution level of the T-RFLP method was in between genus and species within the investigated LAB strains and within family and genus within the investigated Gram-negative strains. The established library was applied to identify the members of bacterial communities in MAP minced meat at the end of the shelf life. The T-RFLP results and plate counts on Man-Rogosa-Sharpe, Violet Red Bile Glucose, and Streptomycin sulfate thallium acetate actidione agars indicated that LAB and B. thermosphacta predominated in meat. The bacterial taxa associated with the T-RFLP results were compared to those identified among plate-grown LAB isolates by numerical ribopattern analysis. Both methods agreed that Leuconostoc spp. and Carnobacterium spp. prevailed in the LAB community in minced meat followed by Lactobacillus algidus, Lactococcus spp. and Weissella spp. Colony identification revealed that Leuconostoc gasicomitatum, L. gelidum, Carnobacterium divergens and C. maltaromaticum were the predominant LAB species. The T-RFLP results were shown to correlate with viable counts of Leuconostoc spp. and B. thermosphacta. The T-RFLP method was found to be a useful tool enabling rapid and high-throughput characterization of psychrotrophic bacteria prevailing in MAP meat.     

Selection of wild lactic acid bacteria isolated from traditional Egyptian dairy products according to production and technological criteria

A total of 755 wild lactic acid bacteria (LAB), belonging to Lactococcus, Lactobacillus, Enterococcus, Streptcoccus, Leuconostoc and Pediococcus isolated from Egyptian raw milk and its products were screened and selected according to their production and technological properties. Many strains showed high yield of biomass in fermentation and some strains were resistant to lyophilization conditions. Most strains showed a good separation after centrifugation, 2% of Lactococcus, 13% of Lactobacillus and 1% of Enterococcus were fast acidifying strains. Aminopeptidase and autolytic activity were generally higher for most lactobacilli compared to other strains. In milk cultures many strains were able to produce pleasant flavours. Antimicrobial activity was detected in 47% of Lactococcus, 21% of Lactobacillus and 41% of Enterococcus strains and some strains produced exopolysaccharides (slime and capsule). Several strains were able to maintain a high activity of two or three technological characteristics together. Detailed information about the characteristics of each strain is available in the culture collection of Faculty of Agriculture Alexandria University (FAAU). A wide variety of LAB from traditional Egyptian dairy products that showed potentially important properties are not only valuable for practical application but they may also provide an expanded gene pool for designing genetic modified strains with improved traits.     

Characterization of enterococci isolated from homemade Bulgarian cheeses and katuk

A collection of 107 lactic acid bacteria (LAB) isolates was obtained from traditional Bulgarian dairy products??homemade cheeses and katuk samples, produced from heat-treated cow, goat, ewe and buffalo milk without the addition of any bacterial starter culture. The samples were collected from mountain region of Rhodope (south part of Bulgaria), Tracian valley and mountain region of Stara Planina (west part of Bulgaria). These LAB produced bacteriocin-like inhibitory substances (BLIS) and proteinases. Preliminary strain determination was performed according to their fermentation ability using API 50CHL and API 20 Strep. Most of the characterized strains (58) belong to genus Enterococcus; 21, 20 and 11 strains were identified as Lactobacillus sp., Streptococcus sp. and Lactococcus sp., respectively. Isolated enterococcal strains were characterized using phenotypic features as well as by DNA typing. The strains were identified as Enterococcus faecium (34), Enterococcus durans (22) and Enterococcus faecalis (2). The proteolytic activity varied from 0.094 to 0.455?mM/L Gly into the group of E. faecium and from 0.109 to 0.487?mM/L Gly into the group of E. durans strains, while both E. faecalis strains showed relatively high proteolytic activity. The samples obtained after 3?h of hydrolysis of ??-casein by E. faecalis B1 strain were further used for mass spectrometry analysis, and 31 peptides were identified.     

Angiotensin-converting enzyme inhibitory activity in Mexican Fresco cheese

The objective of this study was to evaluate if Mexican Fresco cheese manufactured with specific lactic acid bacteria (LAB) presented angiotensin I-converting enzyme inhibitory (ACEI) activity. Water-soluble extracts (3 kDa) obtained from Mexican Fresco cheese prepared with specific LAB (Lactococcus, Lactobacillus, Enterococcus, and mixtures: Lactococcus-Lactobacillus and Lactococcus-Enterococcus) were evaluated for ACEI activity. Specific peptide fractions with high ACEI were analyzed using reverse phase-HPLC coupled to mass spectrometry for determination of amino acid sequence. Cheese containing Enterococcus faecium or a Lactococcus lactis ssp. lactis-Enterococcus faecium mixture showed the largest number of fractions with ACEI activity and the lowest half-maximal inhibitory concentration (IC₅₀; <10 μg/mL). Various ACEI peptides derived from β-casein [(f(193-205), f(193-207), and f(193-209)] and α_S1-casein [f(1-15), f(1-22), f(14-23), and f(24-34)] were found. The Mexican Fresco cheese manufactured with specific LAB strains produced peptides with potential antihypertensive activity.     

Production of Biogenic Amines by Lactic Acid Bacteria Isolated from Uzicka Sausages

The aim of this study was to monitor production of seven biogenic amines (Cadaverine – CAD, Putrescine – PUT, Spermine – SPE, Spermidine – SPD, Histamine – HIS, Tyramine – TYR and Tryptamine – TRY) in selected 24 lactic acid bacteria (LAB) strains. The decarboxylase activity of the microorganisms was studied in growth medium after 24 h cultivation. The ability of 24 LAB isolates cultivated in MRS broth and M17 broth supplement with 0.5% glucose to produce biogenic amines was assessed using liquid chromatography tandem mass spectrometry (LC-MS/MS). The investigation showed that LAB isolated from Uzicka sausage are not significant producers of biogenic amines in vitro.     

Quantitative and qualitative determination of CLA produced by Bifidobacterium and lactic acid bacteria by combining spectrophotometric and Ag-HPLC techniques

Bifidobacterium and lactic acid bacteria (LAB), especially from the genera Lactobacillus and Lactococcus, are commonly used in the production of fermented dairy products due to their potential probiotic characteristics. Moreover, some strains of these microorganisms also have the ability to produce conjugated linoleic acid (CLA) from linoleic acid (LA), which has attracted much attention as a novel type of beneficial functional fermented milk. In the present work 22 probiotic bacteria were tested for the production of CLA, using a UV screening method and HPLC techniques. Five microorganisms, two strains of the genera Bifidobacterium, two Lactobacillus and one Lactococcus were selected for their ability to produce CLA after incubation in skim milk with free LA as a substrate. It was possible to quantify the production of CLA (in the range of 40–50 μg CLA/ml) and identify the CLA isomers produced as C18:2 cis 9, trans 11 (60–65%), C18:2 trans 10, cis 12 (30–32%), C18:2 trans 9, trans 11 and C18:2 trans 10, trans 12 (2–5%).     

The Influences of Natural Zeolite (cliptinolite) on Ammonia and Biogenic Amine Formation by Foodborne Pathogen

The influence of natural zeolite on biogenic amines (BAs) and ammonia (AMN) production by eight common gram negative and positive foodborne pathogens (FBP) were investigated in histidine decarboxylase broth (HDB). Presence of 1% zeolite in the HDB resulted in significantly higher AMN production. Histamine (HIS) production by gram positive bacteria was as low as 0.5 mg/L, whereas Escherichia coli produced 18.96 mg/L of HIS. The use of zeolite also significantly suppressed HIS accumulation by E. coli, Pseudomonas aeruginosa, S. paratyphi A (P < 0.05), although zeolite addition stimulated HIS production by K. pneumonia and Aeromonas hydrophila. The range of tyramine (TYR) production by gram positive bacteria was 1.19 and 4.06 mg/L for Enteroccus faecalis and Listeria monocytogenes respectively. The results of study showed that the effect of zeolite on BAs and AMN production was dependent on bacterial strains, as well as zeolite concentrations used. Practical Application: Natural zeolites are the main absorptive, low-cost material used in agriculture and industry. Although the effect of zeolite on ammonia formation in some industrial systems is well known, there is limited information regarding the impact of zeolite on biogenic amine (BA) production by foodborne pathogens. The data presented in this article will help us to understand the impact of natural zeolite on BA and ammonia production by eight common foodborne pathogens.     

Biocontrol of Listeria monocytogenes by lactic acid bacteria isolated from brewer's grains used as feedstuff in Argentina

Brewer's grains are the most important by-product of the brewery industry and it is mostly used as a protein and energy source in animal nutrition. Listeria monocytogenes is a food-borne pathogen can cause invasive diseases such as meningoencephalitis, sepsis, abortion, and gastroenteritis in humans and several animal species. The aim of this work was to study the antilisterial activity of lactic acid bacteria (LAB) isolated from brewer's grains. The incidence of Listeria spp. in brewer's grains was 3.12%. Twenty-one LAB inhibited the growth of the eight strains of L. monocytogenes. The mean inhibition halo of cell free supernatants of LAB ranged between 11.5 and 24.5 mm. The isolation of lactic acid bacteria with antilisterial activity from brewer's grains is promising based on their capacity to produce antimicrobial compounds. The production of antimicrobial metabolites by LAB in the substrate would generate an unfavorable environment for the growth of the pathogenic bacterium under study.