Typhimurium Counts Research Articles

Comprehensive efficacy of nano-formulated mixed probiotics on broiler chickens’ performance and Salmonella Typhimurium challenge

The increasing recognition of the potential advantages beyond nanoencapsulation of probiotics gained great attention owing to effective properties. Hence, we provided the most in-depth look into the influence of nanoformulated multi strain probiotics; BLB-NPs comprising Bacillus subtilis ATCC19659, Lactobacillus plantarum ATCC8014 and Bifidobacterium bifidum ATCC29521 on growth performance, antioxidant status and intestinal immunity supporting the defense against Salmonella Typhimurium (S. Typhimurium) challenge in broilers chickens. A total of 2,800 one-day-old male Ross 308 boiler chicks were divided into 7 groups; 1 control without additives, 3 probiotics [fed control diets mixed with B. subtilis, L. plantarum and B. bifidum (BLB) at concentrations of 1 × 104 (BLBI), 1 × 106 (BLBII) and 1 × 108 (BLBIII) CFU /kg diet, respectively] and 3 nanoencapsulated probiotics [fed control diets supplemented with BLB loaded nanoparticles (BLB-NPs) at concentrations of 1 × 104 (BLB-NPsI), 1 × 106 (BLB-NPsII) and 1 × 108 (BLB-NPsIII) CFU /kg diet, respectively]. All previous groups were challenged at d 22 of age with S. Typhimurium. Birds fed BLB-NPs II and III exhibited better weight gain and FCR simultaneously with upregulation in nutrients transporters genes (LAT-1, PepT-1, CAT-1 and SGLT1) even after S. Typhimurium challenge. Upregulation of immmune related genes (IL-1β, IL-6, IL-8, MyD88, NF-kB, CCL20, CXCLi2, TLR-2, TLR-4 and SOCS1) was prominently subsided in BLB-NPsIII fed group. The strengthening ability of BLB-NPs for broilers' intestinal barriers was evidenced by augmented expression of JAM, MUC-2, occludin and FABP-2 genes, diminished S. Typhimurium counts and suppressed its virulence related genes (HilA and SopD) with restored histopathological pictures of cecum. Notably, post dietary inclusion of higher levels of BLB-NPsIII, the abundance of beneficial Biofidobacterium and Lactobacillus species was dominated over harmful E. coli ones. Birds fortified with BLB-NPs displayed potent antioxidant potential signified by boosting serum and intestinal antioxidant markers alongside reducing oxidative ones. Overall, the abovementioned positive outcomes of BLB-NPs encouraged their potential application in poultry feed to attain superior performance and elicit protective immunity against S. Typhimurium infection.

Protective effects of potential probiotics Lacticaseibacillus rhamnosus SN21-1 and Lactiplantibacillus plantarum SN21-2 against Salmonella typhimurium infection in broilers

This study aimed to explore the probiotic characteristics of Lacticaseibacillus rhamnosus SN21-1 and Lactiplantibacillus plantarum SN21-2 by genotype and phenotype analysis, assess their safety in vitro and in vivo, and investigate the effects of L. rhamnosus SN21-1 and L. plantarum SN21-2 on Salmonella typhimurium-infected broilers in an in vivo experiment. L. rhamnosus SN21-1 and L. plantarum SN21-2 showed antimicrobial activity against pathogens, including S. Typhimurium, resistance to simulated gastrointestinal digestive fluid, and adhesion to HT-29 cells. In addition, L. rhamnosus SN21-1 and L. plantarum SN21-2 showed no resistance to most common antimicrobial agents and no haemolysis in vitro. Whole-genome sequence analyses of L. rhamnosus SN21-1 and L. plantarum SN21-2 provided basic genomic information, functional genes underlying the probiotic characteristics, and evidence of safety. Furthermore, feeding with L. rhamnosus SN21-1 or L. plantarum SN21-2 for 28 d had no significant effect on the growth or blood biochemical parameters of the broilers, and hematoxylin-eosin staining revealed no liver, spleen, heart, or kidney damage. Additionally, L. rhamnosus SN21-1 or L. plantarum SN21-2 did not translocate to the blood, liver, spleen, heart, or kidney of the broilers. Moreover, L. rhamnosus SN21-1 and L. plantarum SN21-2 significantly reduced S. Typhimurium counts in the faeces and caecal contents of S. Typhimurium-infected broilers and reduced small intestinal bleeding in S. Typhimurium-infected broilers. Consequently, L. rhamnosus SN21-1 and L. plantarum SN21-2 have excellent probiotic characteristics and are safe for use as anti-S. typhimurium probiotics in broilers.

Deletion of an immune evasion gene, steD, from a live Salmonella enterica serovar Typhimurium vaccine improves vaccine responses in aged mice.

Non-typhoidal Salmonella (NTS) generally causes self-limiting gastroenteritis. However, older adults (≥65 years) can experience more severe outcomes from NTS infection. We have previously shown that a live attenuated S. Typhimurium vaccine, CVD 1926 (I77 ΔguaBA ΔclpP ΔpipA ΔhtrA), was immunogenic in adult but not aged mice. Here we describe modification of CVD 1926 through deletion of steD, a Salmonella effector responsible for host immune escape, which we hypothesized would increase immunogenicity in aged mice. Mel Juso and/or mutuDC cells were infected with S. Typhimurium I77, CVD 1926, and their respective steD mutants, and the MHC-II levels were evaluated. Aged (18-month-old) C57BL/6 mice received two doses of PBS, CVD 1926, or CVD 1926 ΔsteD perorally (109 CFU) and the number of FliC-specific CD4+ T cells were determined. Lastly, aged C57BL/6 mice received three doses of PBS, CVD 1926, or CVD 1926 ΔsteD perorally (109 CFU) and then were challenged perorally with wild-type S. Typhimurium SL1344 (108 CFU). These animals were also evaluated for antibody responses. MHC-II induction was higher in cells treated with steD mutants, compared to their respective parental strains. Compared to PBS-vaccinated mice, CVD 1926 ΔsteD elicited significantly more FliC-specific CD4+ T cells in the Peyer's Patches. There were no significant differences in FliC-specific CD4+ T cells in the Peyer's patches or spleen of CVD 1926- versus PBS-immunized mice. CVD 1926 and CVD 1926 ΔsteD induced similar serum and fecal anti-core and O polysaccharide antibody titers after three doses. After two immunizations, the proportion of seroconverters for CVD 1926 ΔsteD was 83% (10/12) compared to 42% (5/12) for CVD 1926. Compared to PBS-immunized mice, mice immunized with CVD 1926 ΔsteD had significantly lower S. Typhimurium counts in the spleen, cecum, and small intestine upon challenge. In contrast, there were no differences in bacterial loads in the tissues of PBS-vaccinated and CVD 1926-immunized animals. These data suggest that the steD deletion enhanced the immunogenicity of our live attenuated S. Typhimurium vaccine. Deletion of immune evasion genes could be a potential strategy to improve the immunogenicity of live attenuated vaccines in older adults.

Antimicrobial effect of dried koruk (Vitis vinifera L.) pomace against food-borne pathogens inoculated in kofte.

This study aimed to investigate the antimicrobial effects of various concentrations of dried koruk pomace (1%, 1.5%, and 2%) used in kofte formulations. To detect the inactivation effect of dried koruk pomace on food-borne pathogens, kofte samples were separately inoculated with Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella Typhimurium at high and low levels. During the storage period, E. coli O157:H7, L. monocytogenes, and S. Typhimurium counts of the samples inoculated with high levels were decreased in the range of 1.1-1.3 log CFU/g, 0.1-0.2 log CFU/g and 1.1-1.2 log CFU/g, respectively. When low inoculum levels were used, E. coli O157:H7 and S. Typhimurium counts of the samples were reduced to an undetectable level at the beginning and after 2 months of storage, respectively. Although L. monocytogenes counts of the samples were reduced to an undetectable level immediately, the counts were increased during storage till the end of the fifth month. The results indicated that dried koruk pomace was more effective in eliminating E. coli O157:H7 and S. Typhimurium than L. monocytogenes inoculated in kofte. The results suggest that using dried koruk pomace in kofte formulations is an effective method to improve the safety of the products, especially when low levels of contamination occur.

Reduced immunogenicity of a live Salmonella enterica serovar Typhimurium vaccine in aged mice.

Non-typhoidal Salmonella (NTS) is responsible for a high burden of foodborne infections and deaths worldwide. In the United States, NTS infections are the leading cause of hospitalizations and deaths due to foodborne illnesses, and older adults (≥65 years) are disproportionately affected by Salmonella infections. Due to this public health concern, we have developed a live attenuated vaccine, CVD 1926 (I77 ΔguaBA ΔclpP ΔpipA ΔhtrA), against Salmonella enterica serovar Typhimurium, a common serovar of NTS. Little is known about the effect of age on oral vaccine responses, and due to the decline in immune function with age, it is critical to evaluate vaccine candidates in older age groups during early product development. In this study, adult (six-to-eight-week-old) and aged (18-month-old) C57BL/6 mice received two doses of CVD 1926 (109 CFU/dose) or PBS perorally, and animals were evaluated for antibody and cell-mediated immune responses. A separate set of mice were immunized and then pre-treated with streptomycin and challenged orally with 108 CFU of wild-type S. Typhimurium SL1344 at 4 weeks postimmunization. Compared to PBS-immunized mice, adult mice immunized with CVD 1926 had significantly lower S. Typhimurium counts in the spleen, liver, and small intestine upon challenge. In contrast, there were no differences in bacterial loads in the tissues of vaccinated versus PBS aged mice. Aged mice exhibited reduced Salmonella-specific antibody titers in the serum and feces following immunization with CVD 1926 compared to adult mice. In terms of T cell responses (T-CMI), immunized adult mice showed an increase in the frequency of IFN-γ- and IL-2-producing splenic CD4 T cells, IFN-γ- and TNF-α-producing Peyer's Patch (PP)-derived CD4 T cells, and IFN-γ- and TNF-α-producing splenic CD8 T cells compared to adult mice administered PBS. In contrast, in aged mice, T-CMI responses were similar in vaccinated versus PBS mice. CVD 1926 elicited significantly more PP-derived multifunctional T cells in adult compared to aged mice. These data suggest that our candidate live attenuated S. Typhimurium vaccine, CVD 1926, may not be sufficiently protective or immunogenic in older humans and that mucosal responses to live-attenuated vaccines decrease with increasing age.

Impact of chitosan embedded with postbiotics from Pediococcus acidilactici against emerging foodborne pathogens in vacuum-packaged frankfurters during refrigerated storage

The objective of the study was to carry out characterization of postbiotics from Pediococcus acidilactici and to assess their efficacy (50% and 100%) in combination with chitosan (0.5 and 1%) against Escherichia coli O157:H7, Salmonella Typhimurium, Listeria monocytogenes on frankfurters during refrigerated storage for 35 days. High amounts of total phenolic content (1708.15 ± 93.28 mg GAE/L) and carboxylic acids, which comprised 74.89% of the total volatiles, were found in the postbiotics. On day 0, the postbiotic-chitosan combinations decreased the E. coli O157:H7, L. monocytogenes and S. Typhimurium counts ranging from 1.58 to 3.21 log10 compared to the control in frankfurters (P < 0.05). Total viable count and number of lactic acid bacteria were effectively reduced in all treatment groups (P < 0.05), and postbiotic and chitosan treatments did not cause any changes in pH and color of the frankfurters. In conclusion, postbiotic-chitosan combinations can be used to reduce the risks that might be associated with E. coli O157:H7, L. monocytogenes, and S. Typhimurium in frankfurters.

Effect of Anolyte on S. Typhimurium and L. monocytogenes Growth in Minced Pork and Beef Cuts.

In this paper, anolyte is considered as a possible disinfectant for inhibiting the growth of bacteria in meat (beef cuts and minced pork). Meat cuts were contaminated with two concentrations of L. monocytogenes and S. Typhimurium, as these are the most common meat pathogens that are closely regulated by the EU, and treated with two different concentrations of anolyte: 20% for beef cuts and 18% for minced pork. Then, the total viable count (TVC), L. monocytogenes count and S. Typhimurium count were determined. In meat cuts and minced pork, anolyte was able to reduce TVC, S. Typhimurium and L. monocytogenes counts effectively, significantly decreasing L. monocytogenes and S. Typhimurium counts after spraying and throughout 29 days of incubation at 0–4 °C. TVC was reduced after spraying and for 10 days of incubation but later increased to be the same as before spraying with anolyte. Anolyte was effective when spraying beef cuts with a 20% solution for 60 s against pathogenic bacteria L. monocytogenes and Salmonella spp. and also when using it at a concentration of 18% from the minced meat mass. Initially, anolyte significantly decreased TVC, however during the storage period (10–29 days) TVC increased but remained significantly lower compared to control. Anolyte was effective in reducing L. monocytogenes and S. Typhimurium counts throughout the study, and after 29 days of incubation, these bacteria could not be detected in the samples treated with anolyte.

Effect of Rheum ribes L. juice on the survival of Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella Typhimurium and chemical quality on vacuum packaged raw beef

The aim of this study was to evaluate Rheum ribes L. juice as a marinade against L. monocytogenes, E. coli O157:H7 and S. Typhimurium in vacuum packed raw beef. The juice was used at levels of 10%, 50%, and 100% for different marination times (2, 6 or 24 h). E. coli O157:H7 and S. Typhimurium counts in the marinated samples at 100% conc. for 24 h were found as 1.1 and 1.7 log10 lower than the control group on day 0, respectively (P < 0.05). L. monocytogenes count was found approx. 3.0 log10 lower than the control group on day 15 (P < 0.05). Total viable count, psychrotrophic bacteria, LAB counts, and pH values were found lower in the 100% conc. marinated samples than control group on day 0 (P < 0.05). A total of 22 volatiles were identified in Rehum ribes L. juice, and ethanol, ethylbenzene and xylene were found as major compounds. Observations showed that the juice exhibited strong antimicrobial activity against tested pathogens depending on the concentrations and marination time. In conclusion, it can be derived that Rheum Ribes L. juice can be used as an acidulant for the decontamination of meat and meat products, and can be a major component of marinades.

Characterization of Pediococcus acidilactici postbiotic and impact of postbiotic-fortified chitosan coating on the microbial and chemical quality of chicken breast fillets

This study was carried out to characterize antioxidant activity, total phenolic content, and the phenolic and flavonoids profile of postbiotic of Pediococcus acidilactici and to evaluate the effects of postbiotics (10% and 50%) alone and in combination with chitosan coating (1%) on the microbial and chemical quality of chicken breast fillets during storage at 4 °C. Antioxidant activity and total phenolic content of the postbiotics were found to be 1291.02 ± 1.5 mg/L TEAC and 2336.11 ± 2.36 mg/L GAE, respectively. The most abundant phenolic was vanillic acid, followed by t-caffeic, gallic, and caftaric acids. The postbiotic-chitosan (50% + 1%) combination decreased L. monocytogenes and S. Typhimurium counts by 1.5 and 2.1 log10 CFU/g, respectively, compared to the control (P < 0.05). This combination decreased the total viable count (TVC), lactic acid bacteria (LAB), and psychrotrophic bacteria count compared to the control (P < 0.05). No differences were found in thiobarbituric acid (TBA) values among the samples during storage (P > 0.05). Postbiotic treatment did not significantly change the pH values and color properties of the breast fillets (P > 0.05). Postbiotic-chitosan combinations extended the shelf-life by up to 12 days compared to the control. In conclusion, the postbiotic-chitosan combination can be used to preserve and improve the microbial quality of chicken meat products.

Antimicrobial Activity and Antibiofilm Potential of Coenzyme Q0 against Salmonella Typhimurium.

Coenzyme Q0 (CoQ0) has anti-inflammatory and anti-tumor effects; however, the antimicrobial and antibiofilm activities of CoQ0 against Salmonella enterica serovar Typhimurium are unknown. Thus, we investigated the bacteriostatic and antibiofilm activities, along with the underlying mechanism, of CoQ0 against S. Typhimurium. The minimum inhibitory concentration (MIC) of CoQ0 against S. enterica serovars Typhimurium was 0.1–0.2 mg/mL (549–1098 µM), and CoQ0 at MIC and 2MIC decreased viable S. Typhimurium counts below detectable limits within 6 and 4 h, respectively. CoQ0 at 20MIC (4 mg/mL) reduced S. Typhimurium on raw chicken by 1.5 log CFU/cm3 within 6 h. CoQ0 effectively disrupted cell membrane integrity and induced morphological changes in the cell, resulting in hyperpolarization, decreased intracellular ATP concentrations, and cellular constituents leakage. Biofilm-associated S. Typhimurium cells were killed by CoQ0 treatment. These findings suggest that CoQ0 could be applied as a natural antibacterial substance for use against S. Typhimurium by the food industry.

Effects of Camu-Camu (Myrciaria dubia) Powder on the Physicochemical and Kinetic Parameters of Deteriorating Microorganisms and Salmonella enterica Subsp. enterica Serovar Typhimurium in Refrigerated Vacuum-Packed Ground Beef

This study aims to evaluate the effects of camu-camu powder (CCP), Amazonian berry fruit with documented bioactive properties, physicochemical meat parameters, and the growth kinetics parameters of S. enterica ser. Typhimurium, psychrotrophic bacteria (PSY), and lactic acid bacteria (LAB) in vacuum-packed ground beef. Batches of ground beef were mixed with 0.0%, 2.0%, 3.5%, and 5.0% CCP (w/w), vacuum-packed as 10 g portions, and stored at 5 °C for 16 days. Centesimal composition analyses (only on the initial day), pH, TBARS, and color were quantified on storage days 1, 7, and 15, while PSY and LAB were counted on days 0, 3, 6, 9, 13, and 16. Another experiment was conducted with the same camu-camu doses by inoculating S. enterica ser. Typhimurium microbial kinetic curves were modeled by the Huang growth and Weibull decay models. CCP decreased TBARS in beef from 0.477 to 0.189 mg MDA·kg−1. No significant differences in meat pH between treated and control samples were observed on day 15. CCP addition caused color changes, with color a* value decreases (from 14.45 to 13.44) and color b* value increases (from 17.41 to 21.25), while color L* was not affected. Higher CCP doses caused progressive LAB growth inhibition from 0.596 to 0.349 log CFU·day−1 at 2.0% and 5.0% CCP, respectively. Similarly, PSY growth rates in the treated group were lower (0.79–0.91 log CFU·day−1) compared to the control (1.21 log CFU·day−1). CCP addition at any of the investigated doses produced a steeper S. enterica ser. Typhimurium inactivation during the first cold storage day, represented by Weibull’s concavity α shape parameter, ranged from 0.37 to 0.51, in contrast to 1.24 for the control. At the end of the experiment, however, S. enterica ser. Typhimurium counts in beef containing CCP were not significantly different (p &lt; 0.05) from the control. Although CCP affects bacterial kinetics, it does not protect ground beef against spoilage bacteria and Salmonella to the same degree it does against lipid peroxidation.

Evaluation of curcumin and copper acetate against Salmonella Typhimurium infection, intestinal permeability, and cecal microbiota composition in broiler chickens

BackgroundInterest in the use of natural feed additives as an alternative to antimicrobials in the poultry industry has increased in recent years because of the risk of bacterial resistance. One of the most studied groups are polyphenolic compounds, given their advantages over other types of additives and their easy potentiation of effects when complexes are formed with metal ions. Therefore, the objective of the present study was to evaluate the impact of dietary supplementation of copper acetate (CA), curcumin (CR), and their combination (CA-CR) against Salmonella Typhimurium colonization, intestinal permeability, and cecal microbiota composition in broiler chickens through a laboratory Salmonella infection model. S. Typhimurium recovery was determined on day 10 post-challenge by isolating Salmonella in homogenates of the right cecal tonsil (12 chickens per group) on Xylose Lysine Tergitol-4 (XLT-4) with novobiocin and nalidixic acid. Intestinal integrity was indirectly determined by the fluorometric measurement of fluorescein isothiocyanate dextran (FITC-d) in serum samples from blood obtained on d 10 post-S. Typhimurium challenge. Finally, microbiota analysis was performed using the content of the left caecal tonsil of 5 chickens per group by sequencing V4 region of 16S rRNA gene.ResultsThe results showed that in two independent studies, all experimental treatments were able to significantly reduce the S. Typhimurium colonization in cecal tonsils (CT, P < 0.0001) compared to the positive control (PC) group. However, only CA-CR was the most effective treatment in reducing S. Typhimurium counts in both independent studies. Furthermore, the serum fluorescein isothiocyanate dextran (FITC-d) concentration in chickens treated with CR was significantly lower when compared to PC (P = 0.0084), which is related to a decrease in intestinal permeability and therefore intestinal integrity. The effect of dietary treatments in reducing Salmonella was further supported by the analysis of 16S rRNA gene sequences using Linear discriminant analysis effect size (LEfSe) since Salmonella was significantly enriched in PC group (LDA score > 2.0 and P < 0.05) compared to other groups. In addition, Coprobacillus, Eubacterium, and Clostridium were significantly higher in the PC group compared to other treatment groups. On the contrary, Fecalibacterium and Enterococcus in CR, unknown genus of Erysipelotrichaceae at CA-CR, and unknown genus of Lachnospiraceae at CA were significantly more abundant respectively.ConclusionsCR treatment was the most effective treatment to reduce S. Typhimurium intestinal colonization and maintain better intestinal homeostasis which might be achieved through modulation of cecal microbiota.

The effects of koruk products used as marination liquids against foodborne pathogens (Escherichia coli O157:H7, Listeria monocytogenes and Salmonella Typhimurium) inoculated on poultry meat

In this study, the effects of marination liquids (MLs) prepared using koruk juice (25% and 50%) and dried koruk pomace (1% and 2%) with or without additives [salt (1%) and thyme (0.1%)] on meat safety were determined. In the first stage, the minimum inhibition concentration (MIC) values of MLs were observed in the range of 6.50% - >50% (v/v). In the second stage, Escherichia coli O157:H7, Listeria monocytogenes and Salmonella Typhimurium were inoculated on poultry meat at high and low inoculum doses (≅ 6 log and ≅ 3 log) and marinated at 4 °C for 2, 24 and 48 h. When high inoculum doses were used, E. coli O157:H7, L. monocytogenes and S. Typhimurium counts on meats were decreased by 0.78–2.52, 0.42–1.50 and 0.58–2.00 log CFU/g, respectively. Marination with 50% koruk juice without additives (ML1) for 48 h was determined as the most effective treatment on E. coli O157:H7 and S. Typhimurium, while the highest reduction of L. monocytogenes was achieved by 50% koruk juice with additives (ML2) for 48 h. The counts of pathogens inoculated on samples at low inoculum doses were reduced to undetectable levels for all treatment times. The results of this study revealed that koruk-based MLs are effective products for providing food safety.

In-package Antimicrobial Treatment of Chicken Breast Meat with High Voltage Dielectric Barrier Discharge–Electric Voltage Effect 1

Microbiological safety and quality of fresh chicken meat are important concerns to industry. The objective of this study was to investigate the effects of in-package, non-thermal high voltage dielectric barrier discharge (HVDBD) treatment on microbial quality, safety, and color of fresh chicken breast meat ( pectoralis major ). Boneless skinless chicken breast meat was collected from a local commercial plant. Non-inoculated meat samples and meat samples inoculated with Campylobacter jejuni and Salmonella Typhimurium were packed in polymeric trays under ambient air conditions. The packaged samples were HVDBD-treated at different voltages (0, 55, 70, or 85 kV) for 180 s, and stored at 4°C for 5 d. Microbial counts (psychrophiles, C. jejuni, S. Typhimurium) and meat color (L* a* b*) were measured before HVDBD treatment and after 5 d of post-treatment storage. Psychrophile growth was inhibited ( P < 0.05) and both foodborne pathogens were reduced ( P < 0.05) by HVDBD treatments regardless of treatment voltage. No differences in psychrophilic and S. Typhimurium counts were observed between the three treatment voltages; however, increasing treatment voltage beyond 55 kV resulted in additional inactivation of C. jejuni . In terms of meat color, there were no differences ( P > 0.05) in a* and b* values between pre-treatment and post-treatment measurements; however, all HVDBD treatments resulted in increased L* value ( P < 0.05). Results indicate that in-package HVDBD treatment can be used to reduce both microbial spoilage and foodborne pathogen risks; however, in-package HVDBD treatment may increase pale color in raw chicken breast meat.

Evaluation of the efficiency of allspice, thyme and rosemary essential oils on two foodborne pathogens in in-vitro and on alfalfa seeds, and their effect on sensory characteristics of the sprouts

Seeds are usual source of contamination and their sprouts are commonly associated foodborne illness. Therefore, the aim of this study was to evaluate the antibacterial vapor phase efficiency of allspice, thyme and rosemary essential oils on two foodborne pathogens in in vitro and on alfalfa seeds, including the chemical profile of the tested EOs and their effect on the sensory characteristics of the sprouts. Antibacterial activity was determined through the minimal inhibitory concentration (MIC) of EOs in vapor phase to inhibit the growth of Listeria monocytogenes and Salmonella Typhimurium in culture media and on alfalfa seeds. Also, the germination and the effect on sensory characteristics of the sprouts were determined. Thyme EO was the most effective of the tested EOs on culture media and on alfalfa seeds, against both bacteria. When rosemary EO was tested against L. monocytogenes in alfalfa seeds, the MIC (4.0 mL/Lair) was higher, compared to the one obtained in culture media (2.7 mL/Lair). But when this EO was tested against S. Typhimurium, the MIC in alfalfa seeds was lower than in culture media (11.7 vs 13.3 mL/Lair). Allspice EO resulted more effective against both bacteria in alfalfa seeds (6.0 mL/Lair for L. monocytogenes and 6.7 mL/Lair for S. Typhimurium), compared to culture media (12.0 mL/Lair for L. monocytogenes and 13.3 mL/Lair for S. Typhimurium). Vapor phase EOs MICs resulted in significant (p ≤ 0.05) decreases of L. monocytogenes and S. Typhimurium counts compared to the control. There also was a significant (p ≤ 0.05) difference between systems (in vitro or on alfalfa seeds) despite the microorganism or the evaluated EO. Treatment alfalfa seed with vapor phase EOs, did not affect the seed germination. Sensory acceptability of the sprouts, obtained of treated seeds, did not were significant (p ≥ 0.05) different of the sprouts obtained from the non-treated seeds.

Inhibition of Salmonella Typhimurium growth in coconut (Cocos nucifera L.) water by hurdle technology

The aim of this study was to evaluate a hurdle technology approach (ultraviolet-C light treatment, vanillin or cinnamaldehyde and storage temperature) for preventing the growth of Salmonella Typhimurium inoculated into coconut water. Inoculated coconut water was treated with UV-C light at different times (3.5, 7 and 10.5 min); immediately, selected natural antimicrobials (vanillin and cinnamaldehyde) were added at fixed concentrations and stored under refrigeration (5 °C) and room (22 °C) temperatures for 30 days. Beta model was used for describing either growth or death kinetics of S. Typhimurium. By themselves, antimicrobials significantly decreased S. Typhimurium counts achieving a maximum reduction of 1.4 ± 0.3 log CFU mL−1 with cinnamaldehyde (100 μg mL−1). Natural antimicrobials and low temperature significantly affected (p < 0.05) S. Typhimurium growth during storage. A 7-min UV-C light exposure allowed the inhibition of S. Typhimurium growth in coconut water containing natural antimicrobials over a 30-day storage at 5 °C. Moreover, a 10.5-min UV-C light treatment per se prevented S. Typhimurium growth in coconut water, regardless of any other hurdles applied. Beta model satisfactorily fits the experimental data. Results might be used for developing a low-cost preservation method for coconut water.

Photodynamic inactivation of foodborne bacteria by eosin Y.

The aim of this study was evaluate the effect of photodynamic inactivation mediated by eosin Y in Salmonella enterica serotype Typhimurium ATCC 14028, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923 and Bacillus cereus ATCC 11778. Bacteria (107 CFU per ml) were incubated with eosin Y at concentrations ranging from 0·1 to 10μmoll-1 , irradiated by green LED (λmax 490-570nm) for 5, 10 and 15min and the cellular viability was determined. Pseudomonas aeruginosa was completely inactivated when treated with 10μmoll-1 eosin Y for 10min. Treatments reduced B. cereus and Salm. Typhimurium counts to 2·7 log CFU per ml and 1·7 log CFU per ml, respectively. Escherichia coli counts were slightly reduced. Staphylococcus aureus presented the highest sensitivity, being completely inactivated by eosin Y at 5μmoll-1 and 5min of illumination. The reduction of cellular viability of photoinactivated Staph. aureus was also demonstrated by flow cytometry and morphological changes were observed by scanning electron microscopy. Eosin Y in combination with LED produced bacterial inactivation, being a potential candidate for photodynamic inactivation. This study evidenced the efficacy of photodynamic inactivation as a novel and promising alternative to bacterial control.

Combination of peracetic acid and ultrasound reduces Salmonella Typhimurium on fresh lettuce (Lactuca sativa L. var. crispa).

Salmonella outbreaks related to fruits and vegetables have been reported being lettuce one of the most contaminated. Peracetic acid (PA) at 50mg/L, sodium dichloroisocyanurate (SD) at 100mg/L, and the combination of SD at 100mg/L and babaçu coconut (Attalea speciosa) oil detergent at 100mg/L were applied to fresh lettuce. Natural contaminant microbiota, physicochemical characteristics, and sensory attributes were evaluated. PA and SD reduced mesophilic aerobic counts by 2.1 and 1.5 log cfu/g, respectively. The most efficient treatment in reducing natural microbiota (i.e., PA) was applied alone and in combination with ultrasound (US). It reduced Salmonella enterica Typhimurium counts to undetectable levels (<1 log cfu/g). US further reduced S. Typhimurium counts by 0.6 log cfu/g in relation to PA, treatment which lessened the pH but increased the titratable acidity of lettuce, but did not cause total color difference. Therefore, the combination of PA and US holds a potential industrial application for sanitization purposes.

Antimicrobial Activity of Acidified Sodium Chlorite and Cell Free Culture Supernatent of Lactic Acid Bacteria against &amp;lt;i&amp;gt;Salmonella&amp;lt;/i&amp;gt; Typhimurium

Most methods used by food industries to decontaminate eggs involve washing of egg surface with various chemicals. In this study, the effectiveness of two organic decontaminants viz., acidified sodium chlorite (ASC) and cell free culture supernatant (CFCS) of two lactic acid bacteria (Lactobacillus plantarum and Pediococcus cerevisiae) was evaluated for the decontamination of spiked Salmonella Typhimurium on chicken egg shell surface. Acidified sodium chlorite at 100 μl/L concentration with the contact time of 20 min completely inhibited S. Typhimurium on egg shell surface while at 50 μl/L concentration 1 - 2 log10 units reduction was observed in counts of S. Typhimurium as compared to control group. Likewise, CFCS of P. cerevisiae completely inhibited the growth of S. Typhimurium on 30 min contact, whereas L. plantarum and combination of both were revealed significant reduction in the counts of S. Typhimurium counts.

Effects of Ozone Wash for Inactivation of S. Typhimurium and Background Microbiota on Lettuce and Parsley

Experiments were done with ozonated water to evaluate its efficacy in reducing the numbers of Salmonella Typhimurium and total mesophilic aerobic bacteria (TMAB) on vegetables and in improving their storage quality. Ozonated water (0.5, 1.0 and 1.5 ppm) treatment for 3, 5 and 10 min caused reductions in the number of TMAB of lettuce and parsley samples ranging between 0.48–1.25 and 0.40–1.03 log units, respectively. The counts of S. Typhimurium on inoculated lettuce samples were reduced by ozonated water in the range of 1.14–3.06 log units reductions, while 0.28–2.57 log units reductions were achieved for parsley samples. On the other hand, the effect of tap water in reducing TMAB and S. Typhimurium counts was found ranging between 0.10–1.20 and 0.44–0.60 log units, respectively. Reduction capacity of ozonated water (1.5 ppm/5 min) on microbial population was also tested in a school kitchen and results were similar with the laboratory findings (P > 0.05). To determine the effects of ozonated water on the storage quality of the samples, TMAB and mold-yeast counts of vegetables were investigated during the storage period at 4C for 15 days. Results of the study showed that ozonated water is mainly useful for reducing S. Typhimurium cells from vegetables. Practical Applications Conventional ozone generators, which needs compressors, air dryers, oxygen concentrators and ozone injectors, are too bulky to be used, in point-of-installations. On the other hand, in ozo-pen system, technology developed in recent years, ozone can be produced directly from the water to be treated itself instead of producing ozone from a dry air or dry oxygen gas source, and the system only needs handheld ozone generator, portable container and water. This study showed that ozonated water, which can be produced practically by ozone probes in a small scale and also at household levels, is a good alternative for improving microbiological quality of fresh produce.