Genomic Characterization and Genetic Profiles of Salmonella Gallinarum Strains Isolated from Layers with Fowl Typhoid in Colombia

Salmonella Gallinarum (SG) is the causative agent of fowl typhoid (FT), a disease that is harmful to the poultry industry. Despite sanitation and prophylactic measures, this pathogen is associated with frequent disease outbreaks in developing countries, causing high morbidity and mortality. We characterized the complete genome sequence of Colombian SG strains and then performed a comparative genome analysis with other SG strains found in different regions worldwide. Eight field strains of SG plus a 9R-derived vaccine were subjected to whole-genome sequencing (WGS) and bioinformatics analysis, and the results were used for subsequent molecular typing; virulome, resistome, and mobilome characterization; and a comparative genome study. We identified 26 chromosome-located resistance genes that mostly encode efflux pumps, and point mutations were found in gyrase genes (gyrA and gyrB), with the gyrB mutation S464T frequently found in the Colombian strains. Moreover, we detected 135 virulence genes, mainly in 15 different Salmonella pathogenicity islands (SPIs). We generated an SPI profile for SG, including C63PI, CS54, ssaD, SPI-1, SPI-2, SPI-3, SPI-4, SPI-5, SPI-6, SPI-9, SPI-10, SPI-11, SPI-12, SPI-13, and SPI-14. Regarding mobile genetic elements, we found the plasmids Col(pHAD28) and IncFII(S) in most of the strains and 13 different prophage sequences, indicating a frequently obtained profile that included the complete phage Gifsy_2 and incomplete phage sequences resembling Escher_500465_2, Shigel_SfIV, Entero_mEp237, and Salmon_SJ46. This study presents, for the first time, the genomic content of Colombian SG strains and a profile of the genetic elements frequently found in SG, which can be further studied to clarify the pathogenicity and evolutionary characteristics of this serotype.

Prebiotics can restrict Salmonella populations in poultry: a review

Antibiotics were over the years, the common supplement used for poultry production. There is a global trend to lessen antibiotics' use due to the contamination of consumed meat with antibiotic residues. Also, there is a concern that human treatments might be jeopardized due to the emergence of antibiotic-resistant bacteria. Prebiotics are attractive supplements, particularly in poultry production, because of the diversity of their effects, including pH amendments, production of short-chain fatty acids (SCFA) and the inhibition of pathogens' growth. The commonly used prebiotics are carbohydrate sources that cannot be easily broken down by chickens. However, they can efficiently be utilized by the intestinal tract's microflora. Oligosaccharides, polysaccharides and lactose are non-digestible carbohydrate sources that are typically used in poultry diets as prebiotics. This review covers current applications and prospects for using prebiotics to improve poultry performance and reduce pathogens, particularly Salmonella, in gastrointestinal tract.

Scientometric Evaluation of 100-year history of Poultry Science (1921-2020)

To have a better contribution to the poultry production community, the Poultry Science Association founded journals including Poultry Science (PS) at 1921. Now, after 100 yr of publishing, PS ranks between the top 10 journals in the category of “agriculture, dairy, and animal science”. One hundred years after publishing the first paper in PS, the poultry industry has been completely revolutionized. Hence, it will be interesting to establish scientometrics study of the PS development during the last century. Therefore, based on findings of the current study, among countries/authors’ collaborations, future research fronts, and possibility of hot topics in the coming years may be predictable. Accordingly, a total of 22,451 articles were retrieved. For content analyses, according to the PS categorization for subject areas, 14 different subject areas were developed, including “behavior, breeding and quantitative genetics, education and extension, health and welfare, immunology, management and environment, metabolism and nutrition, microbiology and virology, modeling, molecular biology, physiology and anatomy, production, products, processing and marketing, and reproduction”. Considering the 100-yr of PS, the most frequent subject area was “nutrition and metabolism” (14,109 articles), and “modeling” (1,114 articles) attracted less scholarly attention. However, considering the last decade (2011–2020), the most important subject area was “molecular biology” (1,420 of 2,466 articles; 57.58%), followed by “modeling” (544 of 1,144 articles; 48.88%). Moreover, the most frequent poultry species/strains were broilers (retrieved in 6,156 articles), followed by laying hens, turkeys, and quail. Considering collaboration of countries and researchers, it can be said that a total number of 108 countries contributed to PS, with the most prolific country being United States (with 9,421 articles; 43.16%), followed by China, Canada, the Netherlands, and Japan. Among the authors, Harms RH (287 articles), and Siegel PB (208) were the most prolific authors, and Siegel PB and Dunnington EA (71 articles) had more collaborations. To study keyword trends, including 3 time periods broilers was the central co-occurrent keyword, while the importance of chickens and turkeys declined during the time. Salmonella spp. was a constant representative of poultry microbiology during 100 yr. While “nutrition and metabolism” was the most important subject area, nutrition-related keywords (major items) were not concentrated and co-occurred with a variety of keywords from different subject areas. While “molecular biology” ranked first over the past decade, the importance of “nutrition and metabolism” should not be ignored. In fact, in recent years, molecular basis of the nutrition has been studied. In big-data era and due to developing the molecular biology technologies, it seems that using mathematical modeling and computational methodologies will increase and probably remains as one of the most attractive research areas for scientists at least in the upcoming future decades.

The possibility of a halal mix probiotic medium for the cultivation of Lactobacillus plantarum N16 and Saccharomyces cerevisiae

This study aimed to determine the effects of interaction between media type (halal mix preparation) and culture mixtures of Lactobacillus plantarum N16 and Saccharomyces cerevisiae (probiotics). A completely randomised factorial design (CRFD) consisting of 2 factors and three replications was used, where factor A was a mixture of Lactobacillus plantarum N16 and Saccharomyces cerevisiae at a ratio of 1:1 (A1); 1:2 (A2) and 2:1 (A3) and factor B was the type of growth media, that is, control (B1), whey tofu, molasses, and fish waste flour (B2), and coconut water, onggok flour and shrimp waste flour (B3). The variables measured were viability, cell biomass, and pH. The results showed interactions between factors A and B, which were significantly different (p <0.05) in terms of viability, cell biomass, and pH. Based on the results of the study, it can be concluded that the mixture of Lactobacillus plantarum N16 and Saccharomyces cerevisiae at a ratio of 2:1 (A3), using coconut water, onggok flour, and shrimp waste flour (B3) as medium and incubated at 36 °C for 24 hours was the best medium. It had a 2.37 viability, 42.33 mg/ml biomass cell, and a pH of 2.37.

Development and Evaluation of a Commercial Direct-Fed Microbial (Zymospore®) on the Fecal Microbiome and Growth Performance of Broiler Chickens under Experimental Challenge Conditions

Simple Summary

Probiotics are recognized for their beneficial health-promoting properties, through competitive exclusion, promoting maintenance of intestinal epithelial integrity and host immune system homeostasis. The use of some spore-forming bacteria from the genus Bacillus has earned interest as a direct-fed microbial in recent years as a potential alternative to antibiotic growth promoters and growth enhancers. The present study evaluates the use of a Bacillus subtilis spore-based direct-fed microbial (Zymospore^®, Vetanco, Villa Martelli, Argentina) compared to an antibiotic growth promoter on the performance of broiler chickens under experimental intestinal challenge conditions. The results suggest that Zymospore^® increases the diversity of the broiler fecal microbiota and is an acceptable substitute for commonly used antibiotic growth promoters under defined and non-defined intestinal dysbiosis conditions.

Abstract

Direct-fed microbials (DFM) are added to broiler chicken diets in order to promote the proliferation of beneficial intestinal bacterial populations, which may lead to gains in performance efficiency and, potentially, reduce the level of enteric pathogens in the broiler chickens. The selection and laboratory evaluation of Bacillus subtilis strains as well as the experimental trial results of a novel Bacillus-based commercial DFM product are described. Fifteen wild-type Bacillus subtilis strains were characterized and assayed for their enzyme production capability, spore resistance to pH, salinity, and temperature, and ability to inhibit the growth of E. coli and Salmonella spp. The final DFM formulation was evaluated and compared to an antibiotic growth promoter (AGPs) in two experimental trials. In Experiment 1, broilers were given a defined challenge of Eimeria spp. and Clostridium perfringens to induce intestinal dysbiosis. The optimal dose of the DFM was determined to be 0.3 kg/ton of feed. At this dose, the broilers fed the DFM performed as well as the Flavomycin^®-fed broilers. Further, intestinal microbiome analysis indicates that the use of the DFM enhances bacterial diversity of the gut flora by day 5 of age, increasing levels of lactic acid bacteria (LAB) and Clostridiales by 25 days of age, which may enhance the digestion of feed and promote growth of the birds. In Experiment 2, the broilers were raised on recycled litter and given an undefined challenge orally to mimic commercial growth conditions. In this trial, the DFM performed as well as the bacitracin methylene disalicylate (BMD)-11%-fed birds. The results of the present studies suggest that this novel DFM, Zymospore^®, improves the performance of broiler chickens under experimental challenge conditions as effective as an AGP, providing a safe and effective substitute to the poultry industry.

Dietary Supplementation with Agave tequilana (Weber Var. Blue) Stem Powder Improves the Performance and Intestinal Integrity of Broiler Rabbits

This study evaluated the effect of Agave tequilana (Weber var. azul) stem powder on the growth performance and the intestinal integrity in rabbits. A total of 120 male rabbits [New Zealand × California] were weaned for 35 days and randomized into four dietary treatments, 15 replicates per treatment, and two rabbits per replicate. The treatments consisted of a basal diet (T0) and dietary supplementation with 0.5% (T1), 1.0% (T2) and 1.5% (T3) of Agave tequilana stem powder. The T3 treatment improved the body weight and average daily gain (p < 0.05) compared to the other groups, without affecting viability and feed conversion ratio (p > 0.05). Furthermore, the T3 treatment enhanced (p < 0.05) the thickness of the muscular and mucous layers, and the height, thickness, and number of villi in the duodenum (p < 0.05). However, this treatment (T3) significantly decreased (p < 0.05) values for the area and depth of the crypts in the duodenum and the villus/crypt ratio. Likewise, in the cecum, T3 treatment provoked a marked decrease (p < 0.05) in the depth and thickness of the crypts. The results indicate that the dietary use with 1.5% of A. tequilana stem powder had a natural growth-promoting effect and enhanced the histomorphometry of the concentric layers (muscle and mucosa), villi, and crypts as indicators of intestinal health in rabbits.

Effectiveness of Administering a Mixture of Lactic Acid Bacteria to Control Salmonella ser. Enteritidis Infections in Broilers

Simple Summary

Salmonella infection is one of the main causes of food poisoning through poultry consumption. Among the various methods used to control this infection, the use of lactic acid bacteria is economical, with little risk of developing antibiotic-resistant bacteria. We selected three Lactobacillus spp. capable of inhibiting Salmonella proliferation in vitro and administered their mixture to 1-day-old chicks to investigate their effect. We suggest that the Lactobacillus mixture formulated in this study aids in protecting poultry farms from Salmonella contamination, further securing food safety.

Abstract

Non-typhoidal Salmonella spp. cause persistent asymptomatic infections in poultry. The consumption of Salmonella-infected poultry products is associated with food poisoning. One of the pathogens that causes such infections is Salmonella ser. Enteritidis (SE). Therefore, alternative measures are required for better control of salmonellosis and to reduce potential antibiotic use. Here, the efficacy of a mixture of lactic acid bacteria (LAB), formulated based on competitive exclusion, was evaluated. The LAB mixture was administered to 1- to 20-day-old chickens using different schemes; the chickens were then inoculated with an SE strain, which was previously identified to be prevalent in broiler breeder farms. Even with short-term administration, the group treated with LAB exhibited lower SE isolation levels in the spleen and cecal content and greater weight gain than that in the control group. This protective efficacy of LAB was retained even after two weeks without LAB administration. According to the results of animal experiments and field tests, evidence of SE infection was absent after treatment of the animals with the LAB formulation used in this study. Thus, this LAB mixture can be used as a potential strategy for protecting poultry farms from Salmonella contamination. This will also help reduce potential antibiotic use.

Probiotic potential of Weissella paramesenteroides MYPS5.1 isolated from customary dairy products and its therapeutic application

Probiotics are viable microorganisms that confer general health benefits to the host when consumed in an adequate concentration. Probiotics may also possess strain-specific therapeutic properties and therefore finding novel strains with probiotic properties is becoming increasingly important. The present study has focused on the isolation of probiotic bacteria from dairy products which possessed potential therapeutic properties. Of the 79 strains isolated, eight were selected for further studies based on a number of traits including biofilm formation, deoxyribonuclease (DNase) activity, agglutination activity, auto-aggregation activity, antibiotic resistance, and antagonistic activity. Strain MYPS5.1 was selected from the eight isolates as the best potential probiotic candidate strain and was subsequently identified as Weissella paramesenteroides by 16S rDNA gene sequencing and sequence analysis. W. paramesenteroides strain MYPS5.1 was resistant to a number of antibiotics and the strain produced a high concentration of exopolysaccharide (EPS) (380.42 mg/L). The functional groups C-H, C = C, N = N, N-H, and C-O in the EPS were identified by using Fourier transform infrared (FTIR) spectroscopy. Computational studies showed that it interacted with cyclin-dependent kinase (CDK), a molecule which is thought to play a role in cancer pathogenesis (REF). Collectively, these results suggest that Weissella paramesenteroides MYPS5.1 is a potential probiotic strain with potential therapeutic properties.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-03074-2.

Association of Heterophil/Lymphocyte Ratio with Intestinal Barrier Function and Immune Response to Salmonella enteritidis Infection in Chicken

Simple Summary

Salmonella represents a serious threat to the poultry industry and human health. The heterophil/lymphocyte (H/L) ratio indicates the robustness and immune system status of the chicken. Thus, the H/L ratio has been used for the selection of chickens that are resistant to Salmonella. However, the mechanisms conferring the resistance ability to the chickens with a low H/L ratio compared to those with a high H/L ratio remain unclear. Therefore, the present study aimed to investigate the association of the H/L ratio with the intestinal barrier function and immune response to Salmonella enteritidis infection in chicken. First, we enumerated the number of goblet cells in the ileum and caecum, measured the ileal villi morphology, and the expression of immune genes in the ileum and caecum of non-infected and SE-infected chickens at 7- and 21-days post-infection. Then, we assessed the correlation with the H/L ratio. The H/L ratio was negatively correlated to the number of goblet cells, IL-1β, IL-8, and IFN-γ ileal expressions, indicating that the individuals with a low H/L ratio displayed enhanced intestinal barrier and immunity. These results suggest that the H/L ratio is associated with intestinal immunity and could be a potential resistance indicator in chickens.

Abstract

The heterophil/lymphocyte (H/L) ratio has been extensively studied to select poultry that are resistant to environmental stressors. Chickens with a low H/L ratio are superior to the chickens with a high H/L ratio in survival, immune response, and resistance to Salmonella infection. However, this disease resistance ability is likely to be associated with enhanced intestinal immunity. Therefore, to expand our understanding of these underlying resistance mechanisms, it is crucial to investigate the correlation between the H/L ratio as a blood immune indicator in live chickens and the intestinal barrier function and immunity. Jinxing yellow chickens H/L line one-day-old were divided into non-infected (NI) and Salmonella enteritidis infected (SI) at 7-days old. After dividing the birds into NI and SI, blood samples were taken for H/L ratios determination, and subsequently, birds from the SI group were infected with Salmonella enteritidis (SE). We assessed the effects of SE infection on the (i) goblet cells number from the ileum and caecum gut-segments, (ii) ileal mucosa morphology, and (iii) immune gene mRNA expressions from the ileum and caecum of NI and SI chickens at 7 and 21 days-post-infection (dpi). We found that the H/L ratio was negatively correlated with most intestinal immune indices, particularly with the goblet cells number and with IL-1β, IL-8, and IFN-γ ileal expressions. In conclusion, these results suggest that the H/L ratio is associated with the intestinal barrier and immune response for SE clearance and that the chickens with a low H/L ratio displayed enhanced intestinal immunity. This study expands the current knowledge that is related to using the H/L ratio to select and breed resistant broiler chickens.

Effects of Lactobacillus acidophilus on the growth performance, immune response, and intestinal barrier function of broiler chickens challenged with Escherichia coli O157

We studied the effects of Lactobacillus acidophilus (L. acidophilus) on the growth performance, intestinal morphology, barrier function, and immune response of broilers challenged with Escherichia coli O157 (E. Coli). A total of 360 1-day-old Cobb male broilers were tested in a 3 × 2 factorial arrangement with 3 dietary L. acidophilus levels (0, 5 × 108 CFU/kg, and 10 × 108 CFU/kg of diet) and 2 disease challenge treatments (control or E. coli challenged). Results showed that E. coli challenge decreased the ADG, ADFI, and BW of broilers from 15 to 21 d (P < 0.05), increased the jejunum intestinal wall thickness, and significantly increased the mortality rate. E. coli challenge significantly (P < 0.05) decreased the serum IgA and IgM contents and peripheral blood CD3+ T cell counts (P < 0.05), increased the serum CRP, DAO, and LPS levels at 21 d; upregulated the mRNA expression of iNOS, IL-8, IL-1β in the jejunum and iNOS in the spleen, and downregulated the occludin and ZO-1 mRNA expression in the ileum at 21 d compared with uninfected birds (P < 0.05). Dietary L. acidophilus supplementation consistently showed higher BW, ADG, ADFI, and jejunum and ileum V:C ratio at 14 d and 21 d in the presence and absence of E. coli challenge (P < 0.05). L. acidophilus supplementation reduced the mortality rate caused by E. coli challenge (P < 0.05), decreased the serum CRP, DAO, and LPS levels at 14 d and 21 d; upregulated the mRNA expression of occludin and ZO-1 in the jejunum and ileum, and downregulated the mRNA expression of iNOS, IL-8, and IL-1β in the jejunum in E. coli challenged birds at 21 d (P < 0.05). Dietary supplementation with L. acidophilus can improve the growth performance, intestinal health, and survival of broilers challenged with E. coli.

Early-Life Immune System Maturation in Chickens Using a Synthetic Community of Cultured Gut Bacteria

The gut microbiome is crucial for both maturation of the immune system and colonization resistance against enteric pathogens. Although chicken are important domesticated animals, the impact of their gut microbiome on the immune system is understudied. Therefore, we investigated the effect of microbiome-based interventions on host mucosal immune responses. Increased levels of IgA and IgY were observed in chickens exposed to maternal feces after hatching compared with strict hygienic conditions. This was accompanied by increased gut bacterial diversity as assessed by 16S rRNA gene amplicon sequencing. Cultivation work allowed the establishment of a collection of 43 bacterial species spanning 4 phyla and 19 families, including the first cultured members of 3 novel genera and 4 novel species that were taxonomically described. This resource is available at www.dsmz.de/chibac. A synthetic community consisting of nine phylogenetically diverse and dominant species from this collection was designed and found to be moderately efficient in boosting immunoglobulin levels when provided to chickens early in life.

IMPORTANCE The immune system plays a crucial role in sustaining animal health. Its development is markedly influenced by early microbial colonization of the gastrointestinal tract. As chicken are fully dependent on environmental microbes after hatching, extensive hygienic measures in production facilities are detrimental to the microbiota, resulting in low colonization resistance against pathogens. To combat enteric infections, antibiotics are frequently used, which aggravates the issue by altering gut microbiota colonization. Intervention strategies based on cultured gut bacteria are proposed to influence immune responses in chicken.

In Vitro Screening of Chicken-Derived Lactobacillus Strains that Effectively Inhibit Salmonella Colonization and Adhesion

Inhibition of Salmonella by Lactobacillus has been a popular research topic for decades; however, the inhibition potential of chicken-derived Salmonella by chicken-derived Lactobacillus has not yet been studied. In this study, 89 strains of Lactobacillus from chicken intestines were isolated by national standard method, Gram staining, physiological, and biochemical experiments and molecular sequencing; The inhibition characteristics of 89 strains of chicken derived Lactobacillus against 10 strains Salmonella (S. Enteritidis SE05, SC31, SC21, SC72 SC74, SC79, SC83, SC87; S. bongori SE47; S. Typhimurium, SC85) were detected by agar inhibition zone, The results showed that the inhibition zone of 24 strains of chicken derived Lactobacillus was more than 10 mm, which indicated that the isolated chicken derived Lactobacillus could effectively inhibit the growth of Salmonella; The drug resistance and bile salt tolerance of these 24 strains were analyzed, The results showed that the standard strains LG and L76 were not resistant, and the other 22 Lactobacillus strains showed different degrees of resistance. The strains LAB24, LAB26, LAB53, LAB69, and L76 showed good tolerance at the concentration of 3 g/L bile salt; Caco-2 cell experiment and flow cytometry were used to analyze the inhibitory effect of chicken derived Lactobacillus on the adhesion of Salmonella to Caco-2 cells, The results showed that 16 probiotics could effectively inhibit the adhesion of Salmonella to Caco-2 cells. Twelve probiotics were identified by molecular biology. The results showed that L76 was Enterococcus faecalis, and the other 11 strains were Lactobacillus.

Sodium Butyrate Reduces Salmonella Enteritidis Infection of Chicken Enterocytes and Expression of Inflammatory Host Genes in vitro

Salmonella Enteritidis (SE) is a facultative intracellular pathogen that colonizes the chicken gut leading to contamination of carcasses during processing. A reduction in intestinal colonization by SE could result in reduced carcass contamination thereby reducing the risk of illnesses in humans. Short chain fatty acids such as butyrate are microbial metabolites produced in the gut that exert various beneficial effects. However, its effect on SE colonization is not well known. The present study investigated the effect of sub-inhibitory concentrations (SICs) of sodium butyrate on the adhesion and invasion of SE in primary chicken enterocytes and chicken macrophages. In addition, the effect of sodium butyrate on the expression of SE virulence genes and selected inflammatory genes in chicken macrophages challenged with SE were investigated. Based on the growth curve analysis, the two SICs of sodium butyrate that did not reduce SE growth were 22 and 45 mM, respectively. The SICs of sodium butyrate did not affect the viability and proliferation of chicken enterocytes and macrophage cells. The SICs of sodium butyrate reduced SE adhesion by ∼1.7 and 1.8 Log CFU/mL, respectively. The SE invasion was reduced by ∼2 and 2.93 Log CFU/mL, respectively in chicken enterocytes (P < 0.05). Sodium butyrate did not significantly affect the adhesion of SE to chicken macrophages. However, 45 mM sodium butyrate reduced invasion by ∼1.7 Log CFU/mL as compared to control (P < 0.05). Exposure to sodium butyrate did not change the expression of SE genes associated with motility (flgG, prot6E), invasion (invH), type 3 secretion system (sipB, pipB), survival in macrophages (spvB, mgtC), cell wall and membrane integrity (tatA), efflux pump regulator (mrr1) and global virulence regulation (lrp) (P > 0.05). However, a few genes contributing to type-3 secretion system (ssaV, sipA), adherence (sopB), macrophage survival (sodC) and oxidative stress (rpoS) were upregulated by at least twofold. The expression of inflammatory genes (Il1β, Il8, and Mmp9) that are triggered by SE for host colonization was significantly downregulated (at least 25-fold) by sodium butyrate as compared to SE (P < 0.05). The results suggest that sodium butyrate has an anti-inflammatory potential to reduce SE colonization in chickens.

Salmonella infection induced intestinal crypt hyperplasia through Wnt/β-catenin pathway in chicken

S. Pullorum is a causative agent of enteric disease of poultry with serious diarrhea. However, the detailed mechanism behind its injury to intestinal mucosa barrier, especially for intestinal stem cells, is unclear. In this study, S. Pullorum were orally administrated to 3 days old chicken to investigate the pathogenesis of S. Pullorum on intestinal mucosal barrier, especially on the proliferation of epithelial cells. We found that S. Pullorum could colonize in the cecum and invade into the liver through intestinal mucosa damage, which caused obvious pathological changes in liver and intestine and even leaded to death, as well as significant reduction of body weight. We also found that S. Pullorum infection enhanced the mRNA expression of IL-1β and IL-6 through TLR4/MyD88 pathway, which was also further verified by the increased lipopolysaccharide (LPS) levels in serum. Furthermore, S. Pullorum increased the depth of crypt and density of PCNA⁺ cells significantly through the over-activation of Wnt/β-catenin signaling pathway. The expression of intestinal stem cells markers Lgr5 and Bmi1 was also increased after S. Pullorum infection to support the crypt hyperplasia. In addition, we verified that S. Pullorum infection enhanced the mRNA expression of IL-1β, TLR4, Lgr5 and Bmi1. Our study indicated that S. Pullorum infection damaged the intestinal mucosa barrier to induce diarrhea, affected the abnormal proliferation of intestinal stem cells by over-activation of Wnt/β-catenin pathway in chicken.

Toxin-mediated competition in weakly motile bacteria

Many bacterial species produce toxins that inhibit their competitors. We model this phenomenon by extending classic two-species Lotka-Volterra competition in one spatial dimension to incorporate toxin production by one species. Considering solutions comprising two adjacent single-species colonies, we show how the toxin inhibits the susceptible species near the interface between the two colonies. Moreover, a sufficiently effective toxin inhibits the susceptible species to such a degree that an 'inhibition zone' is formed separating the two colonies. In the special case of truly non-motile bacteria, i.e. with zero bacterial diffusivity, we derive analytical expressions describing the bacterial distributions and size of the inhibition zone. In the more general case of weakly motile bacteria, i.e. small bacterial diffusivity, these two-colony solutions become travelling waves. We employ numerical methods to show that the wavespeed is dependent upon both interspecific competition and toxin strength; precisely which colony expands at the expense of the other depends upon the choice of parameter values. In particular, a sufficiently effective toxin allows the producer to expand at the expense of the susceptible, with a wavespeed magnitude that is bounded above as the toxin strength increases. This asymptotic wavespeed is independent of interspecific competition and due to the formation of the inhibition zone; when the colonies are thus separated, there is no longer direct competition between the two species and the producer can invade effectively unimpeded by its competitor. We note that the minimum toxin strength required to produce an inhibition zone increases rapidly with increasing bacterial diffusivity, suggesting that even moderately motile bacteria must produce very strong toxins if they are to benefit in this way.

Effect of probiotics on fecal excretion, colonization in internal organs and immune gene expression in the ileum of laying hens challenged with Salmonella Enteritidis

A study was conducted to evaluate the supplementation of probiotics on Salmonella colonization in the ceca and various internal organs as well as immune response in laying hens challenged with Salmonella enterica serovar Enteritidis (SE). Thirty-two 46-wk-old White Leghorns (W-36) were housed individually in wired laying cages under 16L:8D lighting schedule. Hens were challenged individually with nalidixic acid resistant Salmonella Enteritidis (SENAR) after which time they were grouped into four treatments: T1 = SENAR unchallenged control, T2 = SENAR challenged control, T3 = SENAR challenged + 0.05% probiotics (Lactobacillus plantarum), and T4 = SENAR challenged + 0.1% probiotics. All hens, including T1, were euthanized and sampled for the liver with gall bladder (L/GB), ileum, ovary, spleen, and ceca on 7-days post-infection (dpi). Fecal screening was performed on individual hens at both 3 and 6 dpi. No difference was detected between the treatments in cecal SENAR enumeration, and the mean log 10 cfu/gm of SENAR in the ceca was 3.7 for all three treatments. The prevalence of SENAR was lowest for ovary in all treatments and was highest in the spleen. However, there were no significant differences among the treatments in the internal organs. There was no significant difference in the fecal shedding among the treatments on either 3 or 6 dpi, with incidence of positive feces higher at 3 dpi compared to 6 dpi (100 vs. 70% to 80%). SENAR challenge resulted in significant upregulation (P < 0.05) of interleukin (IL)-1β, 6, 10, interferon gamma (IFN-γ), and toll-like receptor (TLR)-4 mRNA expression. Highest level of probiotics resulted in a significant decrease in IFN-γ and elevation of IL-6 and IL-10 gene expression in the ileum. However, IL-1B and TLR-4 gene expression were not different from the SENAR challenge control. This study reveals that there was important regulation of immune genes by probiotics supplementation.

Possibilities of early life programming in broiler chickens via intestinal microbiota modulation

The strong selection in search for a higher growth rate in broilers has resulted in adverse effects such as metabolic disorders, low responsiveness of the immune system, and decreased resistance to pathogens. On the other hand, newly hatched chicks rely mostly on innate immune responses until their gut gets colonized with microbiota. In consequence, early access to active substances or bacteria (pre- and post-hatch) is particularly relevant here because in broilers much of the immune system development occurs early in life. Therefore, early stimulation of beneficial microflora is critical, as it affects, to a great extent, the entire life-span of an individual, and also because the nutritional manipulations of the gastrointestinal tract (GIT) microbiome to enhance productivity and health are rather limited by the resilience of the ecosystem once established in the chicken´s gut. Early life or developmental programming is based on the assumption that the development of diseases later in life can be modulated by perturbations or environmental exposures during critical pre- or early post-natal life. Substances such as plant derivatives, Na butyrate, pre- and probiotics, and β-glucans have been shown to induce beneficial microbiological and immunological changes within the GIT, and therefore are potential candidates to be used as tools to manipulate GIT functionality in the young chicken. Accordingly, substances as these might represent promising candidates to study intestinal microbiota/immune system modulation in broilers´ early stages of breeding. In ovo-delivered prebiotics and synbiotics have been shown to have no adverse effect on the development of the immune system in exposed chickens, while being able to affect lymphoid-organs' morphology in chickens. In ovo procedures have also been proposed as means of promoting a healthy microflora in embryonic guts and stimulating maturation of the cellular and humoral immune responses in central and peripheral immune organs, including those in the GIT. The purpose of this presentation is to discuss the potential usefulness of the instruments currently available to induce early life programming in broilers.

Effect of dietary bacteriophage supplementation on internal organs, fecal excretion, and ileal immune response in laying hens challenged by Salmonella Enteritidis

With the current researches on replacing antibiotics with different dietary interventions, bacteriophages (BP) are potential antimicrobial intervention because of their ability to affect specific bacteria. A study was conducted to evaluate the role of BP against Salmonella enterica serovar Enteritidis (SE) on SE internal organs colonization and ileum immune response in laying hens. Hens were challenged both orally and intracloacally with 108 cfu/mL cells of nalidixic acid resistant Salmonella Enteritidis (SENAR). Thirty-two Single Comb White Leghorns were randomly allocated to 4 dietary treatments: 1) unchallenged control (negative control; T1), 2) SENAR challenged control (positive control; T2), 3) SENAR challenged + 0.1% BP (T3), and 4) SENAR challenged + 0.2% BP (T4). The number of SENAR in the ceca was significantly reduced by 0.2% BP supplementation (P < 0.05) at 7 d post infection (dpi). The respective number of SENAR was reduced from 2.9 log cfu/gm in T2 and T3 to 2.0 log cfu/gm in T4. There was no significant effect of T3 on reduction of numbers of cecal SENAR. A significant reduction of SENAR was observed in the liver with gall bladder (LGB) from 0.75 in T2 to 0.18 log cfu/gm in T4. In the spleen, T4 significantly reduced (P < 0.05) SENAR to 0.56 log cfu/gm compared to T2 and T3 (0.94 log cfu/gm). There was no significant effect of T3 in reduction of prevalence of spleen SENAR. By supplementing 0.2% BP (T4), the SENAR in the ovary was reduced to 0 log cfu/gm. There was a significant reduction (P < 0.05) in fecal SENAR at 6 dpi by T4 (0.71 log cfu/gm) compared to the positive control (1.57 log cfu/gm). The expression of interferon (IFN)-Γ, interleukin (IL)-6, and IL-10 was significantly increased in the ileum by SENAR challenge compared to the negative control. This study suggests that apart from commonly used prebiotics or probiotics, BP are pathogen-specific and can be used as one of the dietary strategies to reduce SE colonization and induce immune modulation in laying hens.

Studies on the growth performance of different broiler strains at high altitude and evaluation of probiotic effect on their survivability

Identification of appropriate breeds of broilers and development of new feed additives is required for the development of poultry industry at high altitude. Therefore, this experiment was conducted first to identify the suitable broiler strain for this region. One week old chicks (150) from three broiler strains, i.e. Vencobb, RIR cross-bred, and Hubbard were randomly selected and divided equally into three groups. All the chicks were provided the same basal diet. The body weight gain and feed: gain responses were significantly (P < 0.05) improved in RIR cross-bred. Mortality was also observed lower in RIR cross-bred. Thereafter, the second trial was conducted in RIR cross-bred to evaluate the effect of probiotic supplementation (T1@ 9 gm/kg feed, T2@ 18 gm/kg feed) on their performance and mortality. No significant differences (P > 0.05) were observed in weight gain, feed intake, feed: gain, and water intake among the three groups, however, mortality from ascites and coccidiosis was reduced in probiotic treated groups. Hence, our results suggest that RIR cross-bred is suitable for rearing in high altitude regions and probiotic supplementation has no beneficial effects on production performance of broilers at high altitude. However, probiotic supplementation indicated lesser loss due to mortality of birds.

The Effects of Agave fourcroydes Powder as a Dietary Supplement on Growth Performance, Gut Morphology, Concentration of IgG, and Hematology Parameters in Broiler Rabbits

This study was conducted to determine the effects of Agave fourcroydes powder as a dietary supplement on the growth performance, gut morphology, serum concentration of IgG, and the hematology parameters of broiler rabbits. A total of 32 rabbits [New Zealand × Californian] were weaned at 35 days. They were randomly selected for two dietary treatments (eight repetitions per treatment), which consisted of a basal diet and a basal diet supplemented with 1.5% dried-stem powder of A. fourcroydes. On day 60 from the initiation of treatment, gut histomorphology (duodenum and cecum), serum concentration of IgG, and hematology parameters were all measured. The results showed that A. fourcroydes powder supplementation improved (P < 0.05) the ADFI, ADG, and final BW. Correspondingly, this treatment increased (P < 0.05) the muscle and mucosa thickness and height and width of villi. However, duodenum crypts depth was lower (P < 0.05) when rabbits were fed with this natural product, compared with the basal diet treatment. Results also indicated that the A. fourcroydes powder increased (P < 0.05) the serum concentration of IgG but did not change the hematology parameters. This data indicates that A. fourcroydes powder, as a supplement, had beneficial effects on increasing the growth performance and serum concentration of IgG, as well as improving the gut morphology without affecting the hematology parameters in broiler rabbits.

Effect of Enterococcus faecium EF 55 on morphometry and proliferative activity of intestinal mucosa in broilers infected with Salmonella Enteritidis

Introduction: The present study aimed to investigate the effect of Enterococcus faecium EF55 on chickens, as well as its influence on proliferative activity of epithelial intestinal cells after infection with Salmonella enterica serovar Enteritidis phage type 4 (SE PT4). Moreover, the length and area of duodenal and jejunal villi of the birds were examined.

Material and Methods: A pool of 80 birds was divided randomly into four groups. Probiotic group (EF) and Salmonella + probiotic group (EFSE) received E. faecium EF55 (109 CFU – 3 g per group/day) during 22 d. Salmonella group (SE) and EFSE group were infected with Salmonella Enteritidis PT4 (108 CFU in 0.2 mL PBS) in a single dose per os on day four of the experiment, whereas control birds (C group) received only 0.2 mL of PBS on that day. Samples were taken on the 4th and 18th day post infection.

Results: Supplementation of feed with E. faecium EF 55 confirmed its selective antibacterial activity against SE PT4. The chickens infected with SE PT4 and fed E. faecium EF55 supplemented diet showed increased proliferative activity of enterocytes in the jejunum in both samplings. Applied probiotic strain demonstrated positive impact on intestinal morphometry in the jejunum of both non-infected groups and in Salmonella-infected chickens. In the latter group, the beneficial effect of E. faecium EF 55 was manifested by more efficient tissue turnover in the jejunum.

Preharvest Food Safety in Broiler Chicken Production

Preharvest food safety in broiler production is a systematic approach to control the introduction, propagation, and dissemination of Salmonella and Campylobacter from breeder flocks to the end of their progeny (broilers) life cycle. New and revised more stringent performance standards for these pathogens at the processing plant level require continuous evaluation of the preharvest management practices and intervention strategies used by the poultry industry. The implementation of stricter biosecurity plans, vaccination of breeder flocks for Salmonella , and usage of feed that is free of animal by-products are some of the measures recommended to control the pathogens. Interventions shown to be effective in experimental settings need to be assessed for their cost-effectiveness and efficiency when applied at the farm level.

Advances and Limitations of Disease Biogeography Using Ecological Niche Modeling

Mapping disease transmission risk is crucial in public and animal health for evidence based decision-making. Ecology and epidemiology are highly related disciplines that may contribute to improvements in mapping disease, which can be used to answer health related questions. Ecological niche modeling is increasingly used for understanding the biogeography of diseases in plants, animals, and humans. However, epidemiological applications of niche modeling approaches for disease mapping can fail to generate robust study designs, producing incomplete or incorrect inferences. This manuscript is an overview of the history and conceptual bases behind ecological niche modeling, specifically as applied to epidemiology and public health; it does not pretend to be an exhaustive and detailed description of ecological niche modeling literature and methods. Instead, this review includes selected state-of-the-science approaches and tools, providing a short guide to designing studies incorporating information on the type and quality of the input data (i.e., occurrences and environmental variables), identification and justification of the extent of the study area, and encourages users to explore and test diverse algorithms for more informed conclusions. We provide a friendly introduction to the field of disease biogeography presenting an updated guide for researchers looking to use ecological niche modeling for disease mapping. We anticipate that ecological niche modeling will soon be a critical tool for epidemiologists aiming to map disease transmission risk, forecast disease distribution under climate change scenarios, and identify landscape factors triggering outbreaks.

Effects of 5-hydroxytryptophan and m-hydroxybenzylhydrazine associated to Lactobacillus spp. on the humoral response of broilers challenged with Salmonella Enteritidis

This study investigates the effects of different doses of serotonin, its precursor 5-hydroxytry-ptophan (5HTP), and m-hydroxybenzylhydrazine inhibitor (NSD1015), administered via intraperitoneal for 5 consecutive days, on behavior and average body weight of broilers. We also measured the humoral immune response and quantification of Salmonella Enteritidis in broilers chickens that received the drugs evaluated and a Lactobacillus pool. The study was divided into 3 experiments: Experiment 1--administration of pharmaceuticals with choice of dosage; Experiment 2--administration of pharmaceuticals and a Lactobacillus pool in birds that were not challenged with S. Enteritidis, and Experiment 3--administration of pharmaceuticals and a Lactobacillus pool in birds challenged with S. Enteritidis. The ELISA was used to scan dosages of intestinal IgA and serum IgY. We used colony-forming units to quantify S. Enteritidis. The concentrations of IgA and IgY did not show significant differences (P>0.05) in Experiment 2. In Experiment 3, NSD1015 associated with Lactobacillus determined higher IgA concentrations, promoting greater stimulus to the immune system than 5HTP. Regarding quantification of S. Enteritidis in the cecal content of birds, 5HTP associated to Lactobacillus determined the smallest number of bacteria, showing possible interaction of 5-hydroxytryptophan and Lactobacillus spp. with the immune system of broiler chickens.

Effect of calcium with and without probiotic, lactose, or both on organ and body weights, immune response and caecal microbiota in moulted laying hens

A total of 72 laying hens were used to investigate the effect of probiotic and lactose on body weight loss, tibia ash, antibody production against sheep red blood cell (SRBC), heterophile-to-lymphocyte (H/L) ratio and gut microbiota in a common moulting method for 14 d. Hens were randomly allocated to 6 experimental groups consisting of (i) full feed (FF), (ii) feed withdrawal (FW), (iii) FW with calcium (Ca), (iv) FW with Ca and offering 7 g/lit lactose in drinking water (CaL), (v) FW with Ca and offering 1 g/lit probiotic in drinking water (CaP), and (vi) FW with Ca and offering a mixture of lactose and probiotic in drinking water (CaLP). The results showed body weight loss in all FW groups were more than 25% that was significantly higher than FF group (p < 0.05). The relative organ weights of hens in FW groups were lower than FF group; especially, it was significant for liver and ovary (p < 0.05). No significant difference was observed between all groups for tibia ash. The highest H/L ratio was related to FW group and offering Ca and lactose numerically and probiotic alone significantly resulted in decrease of this ratio (p < 0.05). The results also showed no significant difference for antibody production against SRBC among experimental groups. The highest coliform bacteria numeration observed in FW group and lactose could significantly reduce this population (p < 0.05). Lactic acid bacteria (LAB) numeration demonstrated a significant difference among treatments, so that FF hens had higher LAB than others (p < 0.05). In addition, FW moulted hens had significantly lower LAB compared to other moulted hens (p < 0.05), except for Ca group. In conclusion, probiotic and lactose was effective in maintaining caecal microbiota balance and improving immunity in hens exposed to moulting.

Isolation and molecular identification of lactic acid bacteria and Bifidobacterium spp. from faeces of the blue-fronted Amazon parrot in Brazil

In Brazil, the blue-fronted Amazon parrot (Amazona aestiva) is a common pet. The faecal microbiota of these birds include a wide variety of bacterial species, the majority of which belong to the Gram-positive lactic acid bacteria (LAB) clade. The aim of this study was to investigate differences in the diversity and abundance of LAB and Bifidobacterium spp. in the cloacae between wild and captive birds and to select, identify and characterise LAB for consideration as a parrot probiotic. Cloacal swabs were collected from 26 wild and 26 captive birds. Bacterial DNA was extracted, and the 16S rRNA genes were amplified. The numbers of PCR-positive Enterococcus, Pediococcus, and Lactobacillus species isolated from wild and captive birds were significantly different (P<0.05). Enterococcus was the most frequently isolated genus, followed by Pediococcus, Lactobacillus, Lactococcus and Bifidobacterium. Enterococcus faecium, Pediococcus pentosaceus, Lactococcus lactis, Lactobacillus coryniformis, Lactobacillus sanfranciscensis and Bifidobacterium bifidum were the most frequently isolated species from all birds. This study increases our understanding of the faecal microbiota, and may help to improve the nutrition and habitat management of captive and wild parrots. The bacterial population identified in the faecal microbiota of clinically healthy wild and captive parrots can serve as a database to analyse variations in the gut microbiota of pathogen-infected parrots and to develop probiotics specific to these genera.

Application of Molecular Approaches for Understanding Foodborne Salmonella Establishment in Poultry Production

Salmonellosis in the United States is one of the most costly foodborne diseases. Given that Salmonella can originate from a wide variety of environments, reduction of this organism at all stages of poultry production is critical. Salmonella species can encounter various environmental stress conditions which can dramatically influence their survival and colonization. Current knowledge of Salmonella species metabolism and physiology in relation to colonization is traditionally based on studies conducted primarily with tissue culture and animal infection models. Consequently, while there is some information about environmental signals that control Salmonella growth and colonization, much still remains unknown. Genetic tools for comprehensive functional genomic analysis of Salmonella offer new opportunities for not only achieving a better understanding of Salmonella pathogens but also designing more effective intervention strategies. Now the function(s) of each single gene in the Salmonella genome can be directly assessed and previously unknown genetic factors that are required for Salmonella growth and survival in the poultry production cycle can be elucidated. In particular, delineating the host-pathogen relationships involving Salmonella is becoming very helpful for identifying optimal targeted gene mutagenesis strategies to generate improved vaccine strains. This represents an opportunity for development of novel vaccine approaches for limiting Salmonella establishment in early phases of poultry production. In this review, an overview of Salmonella issues in poultry, a general description of functional genomic technologies, and their specific application to poultry vaccine developments are discussed.

Toxicological effects of dietary nickel chloride on intestinal microbiota

This study was designed to evaluate the toxicological effect of dietary nickel chloride (NiCl2) on the counts of intestinal bacteria and diversity of microorganisms in broilers. Plate counting and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) assays were used. A total of 240 one-day-old avian broilers chicks were divided into four equal groups and kept on corn-soybean basal diet along with supplementation of 0, 300, 600 and 900 mg/kg NiCl2 for 42 days. Samples were taken at 21 and 42 days of age during the experiment. The bacterial count results showed that dietary NiCl2 in the range of 300 to 900 mg/kg decreased the counts of Bifidobacterium spp. and Lactobacillus, increased Escherichia coli (E. coli) and Enterococcus spp. in the ileum and cecum. PCR-DGGE analysis showed that bacterial band numbers, profile similarity, and the Shannon index of the ileum and cecum were all decreased in the 300, 600, and 900 mg/kg groups at 21 and 42 days of age. In conclusion, dietary NiCl2 affected the amount and diversity of intestinal microbiota in the ileum and cecum of broilers. This finding implies that NiCl2 has toxicological effect on the intestinal ecosystem and, possibly functions.

Performance, histomorphology, and toll-like receptor, chemokine, and cytokine profile locally and systemically in broiler chickens fed diets supplemented with yeast-derived macromolecules

The turnover of intestinal epithelial cells is a dynamic process that includes adequate cell proliferation and maturation in the presence of microbiota and migration and seeding of immune cells in early gut development in chickens. We studied the effect of yeast-derived macromolecules (YDM) on performance, gut health, and immune system gene expression in the intestine of broiler chickens. One thousand eighty 1-d-old birds, with 60 birds per pen and 6 pens per treatment, were randomly assigned to 3 treatment diets; a diet containing monensin (control), control diet supplemented with bacitracin methylene disalycylate (BMD), and BMD diet supplemented with YDM. Feed intake, BW, mortality, ileum histomorphology, and gene expression of Toll-like receptors (TLR2b, TLR4, and TLR21), cytokines [interferon (IFN)-γ, IFN-β, IL-12p35, IL-1β, IL-6, IL-10, IL-8, IL-2, IL-4, and transforming growth factor (TGF)-β4], and cluster of differentiation (CD)40 in the ileum, cecal tonsil, bursa of Fabricius, and spleen were assessed. No significant overall difference in performance in terms of feed intake, BW gain, and G:F was observed among treatments (P > 0.05). The YDM diet resulted in significantly higher villi height and villi height:crypt depth ratio compared with BMD and control diets (P < 0.05). A significantly lower mortality was observed in the YDM treatment compared with both control and BMD treatments. Compared with the control, gene expression analysis in YDM treatment showed no major change in response in the ileum, whereas higher CD40, IFN-β, IL-β, IL-6, TGF-β4, IL-2, and IL-4 in the cecal tonsil; TLR2b, TLR4, TLR21, and TGF-β4 in the bursa of Fabricius; and TLR4, IL-12p35, IFN-γ, TGF-β4, and IL-4 in the spleen was observed (P < 0.05). In conclusion, supplementation of YDM supports pro- and anti-inflammatory cytokine production via T helper type 1 and 2 (Th1 and Th2) cell-associated pathways both locally and systemically with a stronger additive effect in the cecal tonsil in the presence of BMD in the diet of chickens.

Effect of dietary vanadium on intestinal microbiota in broiler

The purpose of this 42-day study was to examine the effect of dietary vanadium on intestinal microorganism diversity in the duodenum, ileum, cecum, and rectum segments of broilers by the plate count and polymerase chain reaction-denaturing gradient gel electrophoresis (DGGE). A total of 420 1-day-old avian broilers were divided into six groups and fed on a control diet or the same diet supplemented with vanadium at the doses of 5, 15, 30, 45, and 60 mg/kg in the form of ammonium metavanadate. In comparison with control group, the dietary vanadium at the doses of 45 and 60 mg/kg could decrease the counts of Bifidobacterium spp. in the intestinal tract at 21 and 42 days of age. With increasing level in dietary vanadium, the counts of Escherichia coli were significantly increased in the ileum, cecum, and rectum and were decreased in the duodenum at 21 and 42 days of age. However, the counts of Lactobacilli were decreased in the cecum and rectum and increased in the ileum of 45 and 60 mg/kg groups. The colonization of these three bacteria could be affected by dietary vanadium. DGGE analysis showed that the number of bands in duodenum, ileum, cecum, and rectum were obviously decreased in the 30, 45, and 60 mg/kg groups at 21 and 42 days of age. In conclusion, the dietary vanadium in excess of 30 mg/kg could alter the amount and diversity of intestinal bacteria in broilers, implying that the structure and initial balance in the intestinal microbiota were disrupted.

Transcriptional profiling of cecal gene expression in probiotic- and Salmonella-challenged neonatal chicks

Probiotics are currently used to improve health and reduce enteric pathogens in poultry. However, the mechanisms by which they reduce or prevent disease are not known. Salmonella are intracellular pathogens that cause acute gastroenteritis in humans, and infections by nontyphoid species of Salmonella also can result in diarrhea, dehydration, and depression in poultry. Frequently, however, no clinical signs of infection are apparent in poultry flocks. In this study, day-of-hatch chicks were challenged with Salmonella enterica serovar Enteritidis (SE) and treated 1 h later with a poultry-derived, Lactobacillus-based probiotic culture (FloraMax-B11, Pacific Vet Group USA Inc., Fayetteville, AR). Cecae were collected 12 and 24 h posttreatment for Salmonella detection and RNA isolation for microarray analysis of gene expression. At both 12 and 24 h, SE was significantly reduced in chicks treated with the probiotic as compared with the birds challenged with only SE (P < 0.05). Microarray analysis revealed gene expression differences among all treatment groups. At 12 h, 170 genes were expressed at significantly different levels (P < 0.05), with a minimum difference in expression of 1.2-fold. At 24 h, the number of differentially regulated genes with a minimum 1.2-fold change was 201. Pathway analysis revealed that at both time points, genes associated with the nuclear factor kappa B complex, as well as genes involved in apoptosis, were significantly regulated. Based on this analysis, probiotic-induced differential regulation of the genes growth arrest-specific 2 (GAS2) and cysteine-rich, angiogenic inducer, 61 (CYR61) may result in increased apoptosis in the cecae of chicks. Because Salmonella is an intracellular pathogen, we suggest that increased apoptosis may be a mechanism by which the probiotic culture reduces Salmonella infection.

Planktonic and biofilm communities from 7-day-old chicken cecal microflora cultures: characterization and resistance to Salmonella colonization

Information implicating bacterial biofilms as contributory factors in the development of environmental bacterial resistance has been increasing. There is a lack of information regarding the role of biofilms within the microbial ecology of the gastrointestinal tract of food animals. This work used a continuous-flow chemostat model derived from the ceca of 7-day-old chicks to characterize these communities and their ability to neutralize invasion by Salmonella enterica serovar Typhimurium. We characterized and compared the biofilm and planktonic communities within these microcosms using automated ribotyping and the Analytical Profile Index biotyping system. Eleven species from eight different genera were identified from six culture systems. Klebsiella pneumoniae was isolated from all planktonic communities and four of the biofilm communities. Three of the communities resisted colonization by Salmonella enterica serovar Typhimurium, two communities suppressed growth, and one community succumbed to colonization. In cultures that resisted colonization, no Salmonella could be isolated from the biofilm; in cultures that succumbed to colonization, Salmonella was consistently found within the biofilms. This study was one of a series that provided a molecular-based characterization of both the biofilm and planktonic communities from continuous-flow culture systems derived from the cecal microflora of chicks, ranging in age from day-of-hatch to 14 days old. The one common factor relating to successful colonization of the culture was the presence of Salmonella within the biofilm. The capacity to sequester the introduced Salmonella into the biofilm appears to be a contributing factor to the inability of these cultures to withstand colonization by the Salmonella.

Advances in enteropathogen control in poultry production

Poultry meat has been associated frequently and consistently with the transmission of enteric pathogens, including Salmonella and Campylobacter. This association has resulted in the development of HACCP-based intervention strategies. These strategies (hurdles) begin with elite breeder flocks and filter down the production pyramid. These hurdles include those already established, such as biosecurity, vaccination, competitive exclusion, pre- and probiotics, feed and water control, and those more experimental, such as bacteriophage or immunoglobulin therapy. The reduction in enteropathogens entering the processing plant, which employs critical control points, further reduce the exposure of consumers to these organisms. The synergistic application of hurdles will result in an environment that is restrictive and detrimental to enteropathogen colonization and contamination.

Characterization of planktonic and biofilm communities of day-of-hatch chicks cecal microflora and their resistance to Salmonella colonization

Recent concerns about the use of antimicrobials in food animals have increased interest in the microbial ecology and biofilms within their gastrointestinal tract. This work used a continuous-flow chemostat system to model the microbial community within the ceca from day-of-hatch chicks and its ability to resist colonization by Salmonella enterica serovar Typhimurium. We characterized the biofilm and planktonic communities from five cultures by using automated ribotyping. Eight species from six different genera were identified. Overall, the planktonic communities were more diverse, with 40% of the cultures containing four or more bacterial species. Eighty percent of the biofilm communities contained only one or two species of bacteria. Enterococcus faecalis was the only species isolated from all communities. None of the resulting microbial communities was able to resist colonization by S. enterica serovar Typhimurium. This is the first study to provide a molecular-based characterization of the biofilm and planktonic communities found in day-of-hatch chicken cecal microflora cultures.

The dual role of bacteriocins as anti- and probiotics

Bacteria employed in probiotic applications help to maintain or restore a host's natural microbial floral. The ability of probiotic bacteria to successfully outcompete undesired species is often due to, or enhanced by, the production of potent antimicrobial toxins. The most commonly encountered of these are bacteriocins, a large and functionally diverse family of antimicrobials found in all major lineages of Bacteria. Recent studies reveal that these proteinaceous toxins play a critical role in mediating competitive dynamics between bacterial strains and closely related species. The potential use of bacteriocin-producing strains as probiotic and bioprotective agents has recently received increased attention. This review will report on recent efforts involving the use of such strains, with a particular focus on emerging probiotic therapies for humans, livestock, and aquaculture.

Planktonic and biofilm community characterization and Salmonella resistance of 14-day-old chicken cecal Microflora-derived continuous-flow cultures

This study evaluated the composition of gastrointestinal bacterial communities in birds during an age in which their susceptibility to Salmonella is highly diminished. One of the challenges to developing probiotics is to develop an efficacious culture of minimal diversity that includes bacteria that are vital contributors to protection from pathogens, but excludes unnecessary species. This study used in vitro continuous-flow culture techniques to test the ability of mixed bacterial cultures acquired from in vivo sources, to resist colonization by a marker Salmonella enterica serovar Typhimurium, and then characterized the constituents of both biofilm and planktonic communities by biochemical, phenotypic, and molecular methods. These cultures, initiated from 14-day-old chicks, were all able to restrict colonization by Salmonella in an average of 10 days. Eighteen species of bacteria from 10 different genera were characterized. However, each culture contained a mixture of only 11 species, which included lactic acid bacteria. Biofilms contained less than 50% of the species found in the planktonic communities. Although not adults, the diversity of microbes within the cecal cultures from 14-day-old birds represents a community complex enough to oppose colonization by a nonindigenous bacteria in vitro. These results describe bacterial mixtures containing less diversity than in previously described avian protective cultures.