Progress 10/01/14 to 09/30/19
Outputs
Target Audience:The target audience for this research project included research scientists, food industry and students . Results of the study were shared with the scientific community through peer-reviewed publications and presentations at the IFT annual meeting. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Over the duration of the project, graduate students were trained in conducting research in microbiology. Specifically, students were engaged in conducting in vitro experiments to characterize the potential probiotics attributes of selected LAB isolates. Furthermore, students were also trained in molecular techniques including RNA isolation, cDNA synthesis, real time PCR, genome sequencing and bioinformatics. In addition to conducting experiments, students also performed statistical analysis of the data to interpret the results of the study. How have the results been disseminated to communities of interest?Data from the study was disseminated to research scientists, food industry and students at the IFT annual meeting (2014, 2015 and 2016). Further results of the study have been published in peer-reviewed journals. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
During this reporting, the select probiotic strains were evaluated for their ability to control Salmonellaon eggs and attenuate virulence.Since Salmonella is known to be transmitted through contaminated eggs, the first part of this objective investigated the ability of probiotics to control Salmonella on eggs. Briefly for this study, eggs were spot inoculated with Salmonella and then sprayed with candidate probiotic cultures. These eggs were then stored and sampled throughout storage to ascertain Salmonella positivity in these samples. Since Salmonella positive eggs subsequently lead to foodborne outbreaks, pathogen control on eggs is expected to reduce the transmission and incidence of egg borne Salmonellosis. Dipping of table eggs in probiotic cultures reduces Salmonella survival on egg surface: Table eggs (University of Connecticut Poultry Farm) were dipped in probiotic solutions for 30 minutes, dried for 1 h in a biosafety hood at room temperature and then inoculated with Salmonella by dipping (Upadhyaya et al., 2013). Following Salmonella inoculation, the eggs were dried and stored at 37.5°C to simulate embryonated egg incubator temperatures. Following incubation, eggs were sampled at day 1 and day 3 post infection for surviving Salmonella populations. Prophylactic dipping of eggs in the probiotic solution significantly reduced Salmonella populations on the egg surface (~ 3 log reduction on d 2) when compared to control (6.4 log CFU on d 2). This demonstrates that dipping with probiotics can be an effective method for reducing Salmonella populations on eggs. Salmonella enterica, responsible for NTS, is a significant public health concern worldwide. In the US, there are approximately 1.2 million illnesses, 23,000 hospitalizations, and 450 deaths attributable to NTS each year. Among the different Salmonella serovars responsible for NTS, the Centers of Disease Control and Prevention (CDC) reported that S. Enteritidis was the most commonly isolated serotype of all Salmonella contributing to 27% of all single etiology outbreaks reported. Chickens serve as natural hosts for S. Enteritidis, with meat and shell eggs being the most commonly implicated vehicles in outbreaks. Although, NTS is mostly self-limiting with fever, headache, abdominal pain, vomiting and diarrhea, it is increasingly being recognized as an important pathogen associated with bacteremia in both the immunosuppressed as well as the immunocompetent patients. The established strategies to control NTS include vaccination and use of antibiotics. However, emergence of multidrug resistant strains and suboptimal efficacy of available vaccines have necessitated the search for alternative therapies against Salmonella infections. Therefore, in light of the high incidence of NTS and the increase in emergence of multidrug resistant S. Enteritidis strains, this study investigated the antimicrobial potential of three probiotic species in attenuating S. Enteritidis virulence and infection using an in vitro tissue culture model. Inhibition of S. Enteritidis adhesion, invasion and translocation human intestinal epithelium by probiotics: Caco-2 monolayers (Human colon carcinoma cell line, American Type Culture Collection) were cultured in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum (D10F; Atlanta Biologicals). The cells were grown in 24-well plates at 37°C in the presence of 7% CO2 for 10-12 days for differentiation and polarization. Probiotic cultures were added to each well and incubated for 1, 4 or 24 h. Unbound bacteria were removed by washing with D10F, and S. Enteritidis was inoculated (MOI; 10:1) with incubation for 1 h. The cells were then washed and bound bacteria released by Triton-X treatment and plated on XLD (Xylose lysine deoxycholate agar) for S. Enteritidis enumeration. For the invasion assay, a gentamicin protection protocol was performed according to Koo et al (2012). Results indicated that pre-exposure to all three probiotic cultures significantly (P<0.05) reduced S. Enteritidis adhesion, invasion and translocation in Caco-2 monolayers by 40% at 24 h. Real time quantitative PCR (RT-qPCR) for Salmonella virulence gene expression: S. Enteritidis was grown to mid-log phase in the presence or absence of the SIP of each probiotic culture separately. Total bacterial RNA was extracted and cDNA was synthesized according to standard protocol. RT-qPCR was performed using primers specific for four Salmonella virulence genes. These include hilA and hilD, which are transcriptional regulators of SPI-1, and fliZ and ygi, which are involved in flagellar motility. All these genes are critical for host colonization by Salmonella in vitro and in vivo (Lostroh et al., 2000; Amy et al., 2004). RT-qPCR results revealed that culturing of S. Enteritidis in the presence of each probiotic culture significantly downregulated all four Salmonella virulence genes compared to control. This demonstrates that in addition to inhibiting Salmonella in chicken and on eggs, the probiotics strains also reduced its pathogenicity in an in vitro model of human salmonellosis. Overall, this project has helped to screen, identify and characterize candidate probiotic strains to control Salmonella. Specifically, L. rhamnosus, L. delbreuckii and L. paracasei were phenotypically and genotypically characterized and identified to i) inhibit Salmonella survival in culture media and on eggs, ii) reduce Salmonella adhesion and invasion in chicken cecal cells and iii) modulate virulence in human intestinal cells in vitro.
Publications
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Progress 10/01/17 to 09/30/18
Outputs
Target Audience:The target audience included the graduate students in agricultural sciences that were mentored during this project period. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?During this reporting period, the graduate student has been trained in conducting research in microbiology, DNA isolation, Genome sequencing and data analysis. Specifically, the student was engaged in conducting in vitro experiments to characterize the attributes of selected LAB isolates. Furthermore, the student has also been trained in molecular techniques including DNA isolation and PCR. In addition to conducting experiments, the student also performed statistical analysis of the data to interpret the results of the study. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?In continuation of the proposed research activities, the select probiotic strains will be evaluated for their ability to control Salmonellain eggs. Since Salmonella is known to be transmitted through contaminated eggs, the first part of this objective will investigate the ability of probiotics to control Salmonella on eggs. Briefly for this study, eggs will be spot inoculated with Salmonella and then sprayed with candidate probiotic cultures. These eggs will then be stored and sampled throughout storage to ascertain Salmonella positivity in these samples. Since Salmonella positive eggs subsequently lead to foodborne outbreaks, pathogen control on eggs is expected to reduce the transmission and incidence of egg borne Salmonellosis. Additionally, the ability of select probiotic candidates to inactivate Salmonella in poultry feed is currently being studied.
Impacts
What was accomplished under these goals?
During this reporting period, the functional and health-promoting properties of select LAB strains including Lactobacillus rhamnosus NRRL B-442 (LR), L. paracasei DUP-13076 (LP) and L. delbreuckii NRRL-548 (LD) were characterized. Briefly, the cultures were evaluated for their ability to inhibit and inactivate pathogens (Salmonella Enteritidis, Salmonella Heidelberg and Salmonella Typhimurium), ability to break down cholesterol and hemolysis). Additionally, their antibiotic susceptibility/resistance profile was determined. Hypocholesterolemic activity The LABs tested were able to assimilate cholesterol in the growth media, and it was 52% for LD, 54% for LR, and 56% for LP. Studies indicate that administration of probiotics exhibited cholesterol-lowering effects in both in vitro and in vivo studies. Lee et al. reported that L. plantarum NR74 was able to take up the cholesterol from the growth media by bile salt hydrolase activity. There are several mechanisms by which probiotics reduce cholesterol level in the host, and they are (i) assimilation of cholesterol during growth, (ii) binding of cholesterol to cellular surface, (iii) disruption of cholesterol micelle, (iv) deconjugation of bile salts, and (v) bile salt hydrolase activity. Antibacterial activity All the probiotic tested, LP, LD and LR completely inhibited the growth of all Salmonella strains by 24 h compared to the control (~8 log CFU/ml). Furthermore, our results revealed that the antimicrobial efficacy varied between different LAB species and the Salmonella serovar. For example, LD completely inhibited (~8 log reduction) SH survival by 10 h. LD was able to reduce SE by ~2 log compared to the control, and SH count was decreased by ~4 log. The LABs were more efficient against ST and SH than SE, since the SE reduction was only by ~1 log at 10 h, while it was ~4 - 6 log for ST and SH. Based on the co-culture assay, LR, LD, and LP have significant antibacterial properties. Hemolytic activity The hemolytic property of bacteria is suggestive of its pathogenicity, and probiotic strains should be tested for the hemolytic activity to evaluate their pathogenicity. In this study, LR, LD, and LP did not hydrolyze sheep blood in vitro which is desirable because they lack infectivity and pathogenicity. This is further supported by the absence of virulence associated genes in their genomes as identified by whole genome sequencing. Antibiotic resistance phenotype Resistance to antimicrobial agents is a significant concern that limits the application of probiotic cultures. The minimum inhibitory concentration was recorded as the lowest antibiotic concentration that inhibited visible growth in the antimicrobial assay. The isolate was considered resistant when they exhibited MICs greater than the MIC breakpoints established by the Clinical and Diagnostic Laboratory Standards Institute (CLSI, 2009). The breakpoints for ampicillin, amoxicillin, piperacillin, imipenem, tetracycline, ciprofloxacin and minocycline were, ≤0.5 µg/ml, ≤4 µg/ml, ≤32 µg/ml, ≤4 µg/ml, ≤4 µg/ml, ≤1 µg/ml and ≤4 µg/ml respectively. LP, LR and LD were screened for susceptibility or resistance to different groups of antibiotics including cell wall inhibitors (ampicillin, amoxicillin, imipenem, piperacillin), nucleic acid inhibitors (ciprofloxacin) and protein synthesis inhibitors (tetracycline and minocycline). The breakpoint values for antibiotic sensitivity varied depending on the LAB isolate. For instance, LR and LD were resistant to ciprofloxacin, while LP was intermediate resistant. On the other hand, LR and LD were intermediately resistant to ampicillin, while LP was sensitive. In general, the LAB isolates were sensitive to all other antibiotics tested, namely, tetracycline, imipenem, minocycline, piperacillin, and amoxicillin. These results are in line with previous studies demonstrating the susceptibility of Lactobacillus genus to penicillins including ampicillin and tetracycline. Although resistance to ciprofloxacin was observed with LR and LD, this has been previously demonstrated in several Lactobacillus strains. Genome sequencing Genome sequencing of L. delbreuckii bulgaricus NRRL B 548 revealed a circular chromosome with 3,010,111 bp with the GC content of 46.6%. There were 163 contigs identified with an average length of 159830 bp, and the largest contig size was 537789 bp. The chromosome contains 371 subsystems with the coding sequence for 3,042 genes. NCBI Prokaryotic Genomes Annotation Pipeline predicted 79 RNA genes (16 rRNAs, 57 tRNAs, and 6 ncRNA). Majority of the genes were found to be associated with carbohydrate metabolism, protein metabolism, RNA metabolism, DNA metabolism, and nucleosides and nucleotides. Moreover, 11 genes with potential probiotic attributes were also identified including genes for adhesion and antimicrobial peptides such as bacteriocin and colicin V.
Publications
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Progress 10/01/16 to 09/30/17
Outputs
Target Audience:During this reporting period the target audience reached included students in the animal science department at the University of Connecticut who are currently being mentored and trained in microbiology, food safety and public health and the scientific community at large through peer-reviewed publications. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?During this reporting period, the graduate student was trained in conducting research in microbiology. Specifically, the student was engaged in conducting in vitro experiments to characterize the potential probiotics attributes of selected LAB isolates. Furthermore, the student has also been trained in molecular techniques including RNA isolation, cDNA synthesis, real time PCR, genome sequencing and bioinformatics. In addition to conducting experiments, the student also performed statistical analysis of the data to interpret the results of the study. How have the results been disseminated to communities of interest?Results of the study were shared with the scientific community at large through peer-reviewed publications. Genome sequences have been deposited at DDBJ/ENA/GenBank. What do you plan to do during the next reporting period to accomplish the goals?In continuation of the proposed research activities, the select probiotic strains will be evaluated for their ability to control Salmonellain eggs. Since Salmonella is known to be transmitted through contaminated eggs, the first part of this objective will investigate the ability of probiotics to control Salmonella on eggs. Briefly for this study, eggs will be spot inoculated with Salmonella and then sprayed with candidate probiotic cultures. These eggs will then be stored and sampled throughout storage to ascertain Salmonella positivity in these samples. Since Salmonella positive eggs subsequently lead to foodborne outbreaks, pathogen control on eggs is expected to reduce the transmission and incidence of egg borne Salmonellosis.
Impacts
What was accomplished under these goals?
During the past reporting period, we had identified three potential probiotic candidates with anti-Salmonella properties. During this reporting period, these strains including Lactobacillus rhamnosus NRRL B-442, L. paracasei DUP-13076 and L. delbreuckii NRRL-548 were further characterized as described under objective 1. Briefly, the cultures were evaluated for their ability to tolerate and survive in the presence of salt, acid and bile salts. Further, their ability to survive gut transit was also evaluated using an in vitro model. Additionally, their cell surface hydrophobicity was also measured as an indication of their ability to adhere to intestinal epithelium. Besides these in vitro assays, a primary chicken cecal epithelium was employed to evaluate the ability of these cultures to adhere to intestinal epithelium. Further genotypic sequencing of the strains was performed to identify specific genetic features of these strainsand for elucidation of their probiotic potential. Results of our experiments, reveal that the three LAB cultures demonstrated a 98% survival in the presence of 5% NaCl, 97% survival under a pH 2-3 and 93-97% survival in the presence of 0.5-1.8% bile in the culture medium. Further,we did not observe any significant reduction in LAB population when grown in simulated gastric and intestinal fluids. The hydrophobicity of the LABs varied between 22-24.5%. The observed hydrophobicity value was least for L. delbreuckii spp. bulgaricus (22%) followed by L. rhamnosus (24%) and L. paracasei (24.5%). These hydrophobicity values which are an indicator of the potential ability of a bacteria to adhere to tissues was further corroborated using in vitro adhesion experiments. The adhesion assay performed using primary chicken cecal epithelial cells revealed that the three LAB strains were able to adhere to the intestinal epithelial cells in significant numbers. Following an hour of attachment, approximately 6 log CFU/well of adhered LAB cells were recovered from the monolayer. Genome sequencing and analysis revealed that genome is composed of a single circular chromosome with a G+C content of 46%. The chromosome contains 2,989 coding sequences, and 75 RNA genes as predicted by NCBI Prokaryotic Genomes Annotation Pipeline (14 rRNAs, 58 tRNAs, and 3 ncRNA). There are 333 subsystems represented in the chromosome. According to RAST analysis, 1,826 protein-coding genes were assigned to a putative functional category, with the most abundant being related to carbohydrate (27%) and protein metabolism (11%). Further, functional analysis revealed that majority of the genes involved in carbohydrate metabolism were associated with disaccharide uptake and synthesis. Additionally, presence of multiple genes involved in bacteriocin and colicin synthesis were detected and no remarkable virulence-associated genes were found.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Muyyarikkandy, M.S. and Amalaradjou, M.A., 2017. Lactobacillus bulgaricus, Lactobacillus rhamnosus and Lactobacillus paracasei Attenuate Salmonella Enteritidis, Salmonella Heidelberg and Salmonella Typhimurium Colonization and Virulence Gene Expression In Vitro. International journal of molecular sciences, 18(11), p.2381.
- Type:
Journal Articles
Status:
Awaiting Publication
Year Published:
2018
Citation:
Muyyarikkandy MS, Alqahtani F, Mandoiu I, Amalaradjou MA. Draft genome sequence of Lactobacillus rhamnosus NRRL B-442, a potential probiotic strain. Genome Announcements.
- Type:
Journal Articles
Status:
Under Review
Year Published:
2018
Citation:
Muyyarikkandy MS, Alqahtani F, Mandoiu I, Amalaradjou MA. Draft Genome Sequence of Lactobacillus paracasei DUP 13076, which exhibits potent antipathogenic effect against Salmonella Enteritidis, S. Typhimurium and S. Heidelberg. Genome Announcements.
- Type:
Other
Status:
Published
Year Published:
2018
Citation:
GenBank Accession no: PKQF01000000
https://www.ncbi.nlm.nih.gov/nuccore/PKQF01000000
- Type:
Other
Status:
Published
Year Published:
2018
Citation:
GenBank Accession no: PKQJ01000000
https://www.ncbi.nlm.nih.gov/nuccore/PKQJ01000000
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Progress 10/01/15 to 09/30/16
Outputs
Target Audience:The target audience for this reporting period includes students in the animal science department at the University of Connecticut who are currently being mentored and trained in microbiology, food safety and public health. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?During this reporting period, the graduate student has been trained in conducting research in microbiology. Specifically, the student was engaged in conducting in vitro experiments to investigate the effect of probiotics on Salmonella colonization. Furthermore, the student has also been trained in molecular techniques including RNA isolation, cDNA synthesis and real time PCR. In addition to conducting experiments, the student also performed statistical analysis of the data to interpret the results of the study. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?In continuation of the proposed research activities, the select probiotic strains will be evaluated for their ability to inhibit Salmonella infection in broilers. Since Salmonella is known to be transmitted vertically through contaminated eggs, the first part of this objective will investigate the ability of probiotics to control Salmonella on embryonated eggs and in the embryo. Briefly for this study, embryonated eggs will be spot inoculated with Salmonella and then sprayed with candidate probiotic cultures. These eggs will then be incubated and sampled throughout incubation to ascertain Salmonella positivity in these samples. Since Salmonella positive eggs subsequently lead to Salmonella positive flocks in the hatchery and on farms, pathogen control at these points of entry is expected to reduce pathogen load in broilers and thereby enhance the microbiological safety of poultry meat.
Impacts
What was accomplished under these goals?
The predilection site for Salmonella in chicken is the cecum. Once it colonizes the cecum, Salmonellainvade the intestinal epithelium and gain entry into the underlying macrophages. Although macrophages serve as line of defense against pathogens, Salmonella has the ability to survive and replicate in the unfavorable environment within the macrophages. Furthermore, contained within the macrophages, Salmonella eventually spread to secondary sites including the liver, spleen and oviduct. Hence beyond reducing intestinal colonization, it is also critical to reduce extra intestinal dissemination of the pathogen. Therefore we investigated the ability of protective cultures to inhibit Salmonella invasion and survival in chicken macrophage cells. Briefly, chicken macrophage cells (HTC) were cultivated in RPMI 1640 containing 10% FBS, and incubated at 37oC and 5% CO2 for 24 h. The cells were then activated using 0.1 µg/ml phorbol myristate acetate (PMA). Following activation, inhibition of Salmonella invasion and survival in macrophages were assayed. Activated macrophages were infected with Salmonella Enteritidis (SE) co-cultured with SICs of probiotic CFSN (L. rhamnosus NRRL B442 - LR, L. paracasei DUP 13076 - LP, and L. delbrueckii subsp. bulgaricus NRRL B548 - LD) for 2 h; with a MOI of 1:100. The unattached Salmonella were washed away using whole media and fresh media supplemented with 100 µg/ml gentamicin added; followed by additional incubation for 1 h at 37oC and 5% CO2. The media in the wells were changed every day with whole media containing 10 µg/ml gentamicin. The cells were washed thrice with PBS, lysed at 2, 24, 48, and 72 h, using 0.1% Triton X-100 before serial dilution and plating to enumerate the surviving population of intracellular Salmonella. In order to understand the underling molecular mechanisms that mediate the anti-Salmonella effect of the protective cultures, we performed real time quantitative PCR. Specifically we investigated the effect of probiotics on the expression of Salmonella virulence genes including motA, flgG, hilA, hilD, sipA, sipB, invH, sopB, pipB, and spvB Results: All three probiotics tested were able to significantly reduce Salmonella survival in chicken macrophages. Among the three probiotics tested, only LR was able to significantly reduce SE invasion in HTC by 20%. However, LR, LD and LP were effective in significantly reducing SE survival in chicken macrophages. For example, LR significantly reduced SE survival by 50%, 100% and 100% at 24, 48 and 72 h respectively. Furthermore, following probiotic treatment, all the genes tested showed a significant reduction in their expression and overall ~2-35 fold change in gene expression was observed with SE. Genes including invH, hilA, hilD, and pipB were downregulated by ~2-5 fold by LP, LD and LR in SE. Similarly, a comparable reduction in the expression sipA, sipB, sopB, and spvB was observed with SE. With respect to the probiotic candidates, LP was found to be significantly more effective in modulating Salmonella virulence gene expression when compared with LR and LD. Downregulation of these genes would cause reduced adhesion and invasion of Salmonella in the host cells. Thus, corroborating the results observed in our study where exposure to probiotics significantly reduced adhesion and invasion of SE in cecal epithelial cells and macrophages.
Publications
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Progress 10/01/14 to 09/30/15
Outputs
Target Audience:The target audience for this reporting period included a graduate student in agricultural sciences who was mentored in STEM research. The scientific community who were informed of our study and its results through a presentation at the IFT annual meeting, July 2015. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?This project has provided opportunities for training a graduate student in STEM research. Specifically, the PI is mentoring a graduate student in conducting research in microbiology. The student has been successfully trained in the design of experiments, their execution, data collection, analysis and interpretation. Further, the student was also trained in writing scientific abstracts, preparation of scientific posters and communicating research through oral presentations. How have the results been disseminated to communities of interest?The results from this study were disseminated to the scientific community through the IFT annual meeting. Specifically, the data from this study was presented to the members of the Food Microbiology division of IFT through a poster and oral presentation during the 2015 IFT annual meeting held in Chicago. What do you plan to do during the next reporting period to accomplish the goals?In continuation of the proposed research activities, the select probiotic strains will be evaluated for their ability to inhibit Salmonella invasion and survival in chicken macrophages. Survival and replication of Salmonella in macrophages provides a route for the pathogen dissemination to other internal organs in chickens. Hence reduction of Salmonella survival in macrophages will help reduce systemic spread of Salmonella. Further, molecular assays (quantitative PCR) will be performed to identify the underlying mechanisms that help mediate probiotic induced reduction in Salmonella virulence and infection in vitro.
Impacts
What was accomplished under these goals?
Salmonella enterica is a major foodborne pathogen in the United States. Among the different Salmonella serovars, Salmonella Enteritidis, Salmonella Typhimurium and Salmonella Heidelberg have been most commonly associated with foodborne illness. Chickens serve as natural hosts for Salmonella, with meat and shell eggs being the most commonly implicated vehicles in outbreaks. Salmonella colonization in chicken is characterized by initial attachment to the intestinal epithelium followed by invasion and translocation resulting in systemic dissemination to liver, spleen and oviduct. Therefore reducing Salmonella populations in the chicken intestinal tract would reduce subsequent contamination of poultry meat and eggs. Hence, this study investigated the efficacy of select probiotics to inhibit intestinal invasion and subsequent systemic spread of Salmonella Enteritidis, Salmonella Heidelberg and Salmonella Typhimurium Objectives 1 and 2 have been targeted during the last year. To accomplish these objectives, 23 probiotic strains were screened for their potential anti-Salmonella properties using well diffusion and spot on lawn assays. Following this initial screening, co-culture assays were performed to identify potential probiotic candidates that could inactivate Salmonella in a broth system. From these initial assays, 10 strains were identified for further evaluation. These strains were evaluated for their ability to adhere to and reduce Salmonella colonization in an avian intestinal epithelial cell line (BATC; Budgerigar abdominal tumor cells) and primary chicken cecal epithelial cells (CEC). Additionally, the effect of probiotics on Salmonella motility was evaluated. All experiments had triplicate samples and were replicated three times. Results: Initial co-culture experiments revealed that ten probiotic isolates completely inactivated all Salmonella serovars by 24 h of incubation. Following initial screening, further assays were performed using Lactobacillus acidophilus NRRL-B-100, L. casei ATCC-334, L. delbreuckii sub sp. Bulgaricus NRRL-B-548, L. delbreuckii sub sp. Lactis NRRL-B-4525, L. gasseri NRRL-B-4240, L. johnsonii NRRL-B-2178, L. paracasei DUP-13076, L. plantarum NRRL-B-4496, L. rhamnosus NRRL-B-442 and Lactococcus lactis NRRL-B-633. Pre-exposure of the BATC and CEC monolayers to probiotic cultures for 24 h significantly (P<0.05) reduced Salmonella invasion by 71-100%. Results of the study indicate that probiotic cultures inhibited Salmonella motility, intestinal colonization and prevented further SE dissemination in vitro.
Publications
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