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This study aimed to evaluate the ability of biofilm formation by L. monocytogenes from the meat processing industry environment, as well as the use of different combinations of detergents, sanitizers, and UV-A radiation in the control of this microorganism in the planktonic and sessile forms. Four L. monocytogenes isolates were evaluated and showed moderate ability to form biofilm, as well as carried genes related to biofilm production (agrB, agrD, prfA, actA, cheA, cheY, flaA, sigB), and genes related to tolerance to sanitizers (lde and qacH). The biofilm-forming isolates of L. monocytogenes were susceptible to quaternary ammonium compound (QAC) and peracetic acid (PA) in planktonic form, with minimum inhibitory concentrations of 125 and 75 ppm, respectively, for contact times of 10 and 5 min. These concentrations are lower than those recommended by the manufacturers, which are at least 200 and 300 ppm for QAC and PA, respectively. Biofilms of L. monocytogenes formed from a pool of isolates on stainless steel and polyurethane coupons were subjected to 14 treatments involving acid and enzymatic detergents, QAC and PA sanitizers, and UV-A radiation at varying concentrations and contact times. All treatments reduced L. monocytogenes counts in the biofilm, indicating that the tested detergents, sanitizers, and UV-A radiation exhibited antimicrobial activity against biofilms on both surface types. Notably, the biofilm formed on polyurethane showed greater tolerance to the evaluated compounds than the biofilm on stainless steel, likely due to the material's surface facilitating faster microbial colonization and the development of a more complex structure, as observed by scanning electron microscopy. Listeria monocytogenes isolates from the meat processing industry carry genes associated with biofilm production and can form biofilms on both stainless steel and polyurethane surfaces, which may contribute to their persistence within meat processing lines. Despite carrying sanitizer tolerance genes, QAC and PA effectively controlled these microorganisms in their planktonic form. However, combinations of detergent (AC and ENZ) with sanitizers (QAC and PA) at minimum concentrations of 125 ppm and 300 ppm, respectively, were the most effective.

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This study aimed to investigate the occurrence and the genetic diversity of Salmonella enterica subsp. enterica in sausages from Southern Brazil, evaluate virulence genes and determine the phenotypic and genotypic basis of antimicrobial and sanitizer resistance. Salmonella was detected in sausage samples with an overall prevalence of 5.5%. The prevalent serovars were S. Infantis and S. Rissen. Pulsed-field gel electrophoresis (PFGE) analysis yielded nine distinct PFGE profiles, and some of them were recurrently recovered in the same establishment on different dates. Among tested isolates, 28.5% showed resistance to at least one antimicrobial agent and a multidrug-resistance (MDR) profile was observed in 21.4%. Resistance occurred most frequently to ampicillin, sulfonamide, trimethoprim/sulfamethoxazole, and trimethoprim. Regarding the genotypic antimicrobial resistance profile, S. Schwarzengrund carried tet(B), strA, strB, and sul2 genes. Benzalkonium chloride and chlorhexidine were more effective than peracetic acid and sodium hypochlorite, showing lower minimum inhibitory concentration values. Six Salmonella serovars were found, demonstrating a potential risk of salmonellosis associated with consuming this food. Salmonella carrying virulence genes, MDR profile, and tolerance to sanitizers is a public health concern and a challenge for the food industry, suggesting that new strategies should be developed to control this pathogen. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-023-05809-w.

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Pediococcus pentosaceus is a lactic acid bacterium that has probiotic potential proven by studies. However, its viability can be affected by adverse conditions such as storage, heat stress, and even gastrointestinal passage. Thus, the aim of the present study was to microencapsulate and characterize microcapsules obtained by spray drying and produced only with whey powder (W) or whey powder combined with pectin (WP) or xanthan (WX) in the protection of P. pentosaceus P107. In the storage test at temperatures of - 20 °C and 4 °C, the most viable microcapsule was WP (whey powder and pectin), although WX (whey powder and xanthan) presented better stability at 25 °C. In addition, WX did not show stability to ensure probiotic potential (< 6 Log CFU mL-1) for 110 days and the microcapsule W (whey powder) maintained probiotic viability at the three temperatures (- 20 °C, 4 °C, and 25 °C) for 180 days. In the exposition to simulated gastrointestinal juice, the WX microcapsule showed the best results in all tested conditions, presenting high cellular viability. For the thermal resistance test, WP microcapsule was shown to be efficient in the protection of P. pentosaceus P107 cells. The Fourier transform infrared spectroscopy (FTIR) results showed that there was no chemical interaction between microcapsules of whey powder combined with xanthan or pectin. The three microcapsules produced were able to protect the cell viability of the microorganism, as well as the drying parameters were adequate for the microcapsules produced in this study.

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The aim of the work was to evaluate antagonistic activity of Lactobacillus spp. and Bifidobacterium spp. in vitro against cariogenic Streptococcus mutans UA 159 and viability in chewing gum, during storage. Antagonistic activity was evaluated in vitro by the "spot on the lawn" test. Two bacteria were chosen and subjected to lyophilization and microencapsulation using the atomization method, containing polyvinylpyrrolidone polymer and lactose as encapsulating agents. For application in food matrices, four treatments were elaborated: chewing gum containing lyophilized B. lactis B94 (BLL), microencapsulated B. lactis B94 (BLE), lyophilized L. brevis (LBL), and microencapsulated L. brevis (LBE). Both microorganisms demonstrated a high capacity for inhibition against S. mutans, when compared to oral antiseptic chlorhexidine 0.2% in vitro, and according to the test of sensitivity profile to proteolytic enzymes, all the bacteria tested are producers of antimicrobial peptides, resulting in the inhibitory activity of the cariogenic bacterium. Furthermore, the viability of B. lactis B94 and L. brevis was maintained after microencapsulation, indicating that the process was efficient, with no significant difference (p < 0.05) between the results. And, in the chewing gum containing the bacteria during the storage period (33 days), it was found that cell immobilization did not significantly influence (p < 0.05) the counts of L. brevis but benefited the viability of B. lactis B94. Therefore, both probiotic bacteria are producers of antimicrobial substances with the ability to inhibit S. mutans, in vitro. The microencapsulation was considered efficient since it influenced the viability of B. lactis B94 (> 8 log CFU/g); however, the microencapsulation did not influence the viability of L. brevis since in both lyophilized and encapsulated form; the concentration of the bacteria remained above 8 log CFU/g during the storage period of the chewing gum.

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Clinical evidence suggests that neuroinflammation, activation of the immune system, and the composition of the intestinal microbiota are involved in the pathology of depression. This study evaluated the effectiveness of a probiotic intervention using Lactococcus lactis subsp. cremoris LL95 in ameliorating mood disorders in a lipopolysaccharide (LPS)-induced depression-like mouse model. C57BL/6 mice were randomly divided into four groups and treated with 5 mg/kg LPS via intraperitoneal injection to induce depression-like symptoms, followed by oral administration of LL95 for one week (1â€¯× 109 CFU/mouse). The animals were then subjected to a series of behavioral assessments, including open field, sucrose preference, and forced swimming tests. In addition, we evaluated the levels of reactive oxygen species, tumor necrosis factor-α, and interleukin-1ß in the hippocampal tissues of these animals, and also determined their fecal lactic acid bacteria (LAB) content. LL95 intervention improved LPS-induced depression-like behaviors in mice, including decreased sucrose preference and increased immobility time in the forced swim test. LL95 treatment reversed the LPS-induced increase in hippocampal levels of reactive oxygen species and tumor necrosis factor-α, and of interleukin-1ß to a lesser extent. Furthermore, LL95 intervention increased the fecal LAB content in these animals, suggesting changes in the gut microbiota. These findings suggest that LL95 exerts antidepressant-like effects in LPS-induced depression, which may be attributed to modulation of the oxidative status and pro-inflammatory cytokine expression in the hippocampus and alteration in the LAB content of the gut microbiota.

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ABSTRACT: The traffic in international animal products can become a public health hazard when legal import sanitary procedures are not followed. In Brazil, due to its extensive border area, the importation of animal products is a common practice in many areas, especially in Rio Grande do Sul, a state that borders Argentina and Uruguay. The objective of this study was to evaluate the presence of veterinary drug residues (antibiotics and antiparasitics) in animal products consumed in Rio Grande do Sul. The presence of residues of veterinary antibiotics and antiparasitics was assessed in 189 meat (beef, pork, and chicken), processed dairy, and meat product samples bought in Argentina (n = 90) and Uruguay (n = 99). Residues of these veterinary drugs were detected in 50 (26.45%) of the samples; 28 samples (14.81%) had antibiotic residues, and 22 samples (11.64%) had antiparasitic residues. Of the 50 positive samples, 40% (15 from Argentina and 5 from Uruguay) had residues above the maximum residue limits (MRLs). Of these 20 samples, 12 had antiparasitic residues above the MRLs (11 beef samples had ivermectin and 1 pork sample had ivermectin and doramectin) and 8 had antibiotic residues above the MRLs (2 pork and 2 sausage samples had doxycycline, 2 cheese samples had doxycycline and chlortetracycline, 1 poultry meat sample had chloramphenicol, and 1 cheese sample had monensin). Because of the potential toxic effects on humans and the potential for pathogens to develop antibiotic resistance, the presence of these residues above the MRLs is a potential risk to public health. The negative impact of consumption of imported animal products can be reduced by implementation of an effective surveillance system and educational campaigns for the general population.

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Salmonella spp. causes foodborne diseases related to the consumption of contaminated foods, especially poultry products. This study aimed to investigate the occurrence of Salmonella spp. serovars in raw eggs from supermarkets and street food markets in southern Brazil, to analyze virulence genes, resistance profiling to antimicrobials and sanitizers, and to determine the susceptibility of the isolates to Butia odorata extract. Among 160 samples analyzed, just two (1.25%) were positive for Salmonella spp.. One positive sample was from egg yolk (S. enterica serovar Gallinarum, isolate S28), and another one was from eggshell (S. enterica serovar Panama, isolate S37). Regarding the virulence genes, the isolate S37 harbored all the genes evaluated (hilA, invA, spvC, sefA, and pefA), while the isolate S28 did not harbor the pefA gene. The isolate S28 was resistant to tobramycin, azithromycin, and trimethoprim, while the isolate S37 showed resistance profile just to nalidixic acid. However, none of the resistance genes evaluated were identified. Both isolates showed resistance to benzalkonium chloride, chlorhexidine digluconate, sodium hypochlorite, and peracetic acid, presenting high MIC values for these sanitizers. In contrast, B. odorata extract showed antimicrobial activity against the isolates S28 and S37, however, more studies are needed to prove its potential as a natural antimicrobial compound.

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ABSTRACT: The goals of this study were to evaluate the persistence and the virulence potential of Listeria monocytogenes isolated from beef carcasses obtained in processing facilities in the southern region of Rio Grande do Sul, Brazil, based on pulsed-field gel electrophoresis (PFGE), invasion ability in human colorectal carcinoma cells (HCT-116), internalin A (InlA) expression by Western blot, and identification of mutation points in inlA. PFGE profiles demonstrated that L. monocytogenes isolates were grouped based on their previously identified lineages and serogroups (lineage I: serogroup IIb, n = 2, and serogroup IVb, n = 5; lineage II: serogroup IIc, n = 5). Isolates with indistinguishable genetic profiles through this method were obtained from different slaughterhouses and sampling steps, with as much as a 3-year interval. Seven isolates showed high invasion ability (2.4 to 7.4%; lineage I, n = 6, and lineage II, n = 1) in HCT and expressed InlA. Five isolates showed low cell invasion ability (0.6 to 1.4%; lineage I, n = 1, and lineage II, n = 4) and did not express InlA, and two of them (lineage II, serogroup IIc) presented mutations in inlA that led to premature stop codon type 19 at position 326 (GAA → TAA). The results demonstrated that most L. monocytogenes isolates from lineage I expressed InlA and were the most invasive in HCT, indicating their high virulence potential, whereas most isolates from lineage II showed attenuated invasion because of nonexpression of InlA or the presence of premature stop codon type 19 in inlA. The obtained results demonstrated that L. monocytogenes with indistinguishable PFGE profiles can persist or be reintroduced in beef processing facilities in the studied region and that differences in their virulence potential are based on their lineages and serogroups.

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Survival of Lactococcus lactis subsp. lactis R7, microencapsulated with whey and inulin, was analyzed when added to blueberry juice, milk, and cream. For 28 days, cell viability was evaluated for storage (4 °C), simulated gastrointestinal tract (GIT), and thermal resistance. All matrices demonstrated high cell concentration when submitted to GIT (11.74 and 12 log CFU mL-1), except for the blueberry juice. The thermal resistance analysis proved the need for microencapsulation, regardless of the food matrix. The results indicate that L. lactis R7 microcapsules have potential for application in different matrices and development of new probiotic products by thermal processing.

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Staphylococcus aureus is one of the most common pathogens associated with food poisoning, which is caused by the ingestion of food contaminated with staphylococcal enterotoxins (SE). Our study aims at evaluating the occurrence and expression of five SE genes (sea, seb, sec, sed, and see) in S. aureus previously isolated from broiler carcasses. Besides that, it also presents an in vitro analysis of the effects of sodium chloride and temperature on the levels of transcriptional expression. A total of 30 S. aureus isolates were investigated for the presence of SEs by PCR assay. The expression level and the effects of sodium chloride (2.5% NaCl), as well as temperature (8 ºC and 12 ºC), on the transcriptional expression, were evaluated by a quantitative reverse transcription PCR (RT-qPCR). Twelve isolates carried at least one of the SE genes. Among them, five representative isolates presented transcriptional expression for at least one gene. Both sodium chloride and low temperatures interfered with the expression of the SE genes, decreasing their values. However, one isolate displayed relative expression 2.25 times higher for sed gene than S. aureus FRI 361 in optimal conditions (p < 0.05), demonstrating their toxigenic potential even under salt stress. There was no evidence of enterotoxin gene expression at 8 ºC.

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