Joshua Gong

Antimicrobial activity of essential oils and structurally related synthetic food additives towards selected pathogenic and beneficial gut bacteria.

Aims:  To assess the potential of essential oils and structurally related synthetic food additives in reducing bacterial pathogens in swine intestinal tract.

Interactions between commensal bacteria and the gut-associated immune system of the chicken

Abstract The chicken gut-associated lymphoid tissue is made up of a number of tissues and cells that are responsible for generating mucosal immune responses and maintaining intestinal homeostasis. The normal chicken microbiota also contributes to this via the ability to activate both innate defense mechanisms and adaptive immune responses. If left uncontrolled, immune activation in response to the normal microbiota would pose a risk of excessive inflammation and intestinal damage. Therefore, it is important that immune responses to the normal microbiota be under strict regulatory control. Through studies of mammals, it has been established that the mucosal immune system has specialized regulatory and anti-inflammatory mechanisms for eliminating or tolerating the normal microbiota. The mechanisms that exist in the chicken to control host responses to the normal microbiota, although assumed to be similar to that of mammals, have not yet been fully described. This review summarizes what is currently known about the host response to the intestinal microbiota, particularly in the chicken.

Effects of zinc bacitracin, bird age and access to range on bacterial microbiota in the ileum and caeca of broiler chickens

Aims:  Determining the effects of zinc bacitracin, bird age and access to range on bacterial microbiota in the ileum and caeca of broilers.

Effects of lactobacilli on cytokine expression by chicken spleen and cecal tonsil cells.

ABSTRACT Lactobacillus acidophilus, Lactobacillus reuteri, and Lactobacillus salivarius are all normal residents of the chicken gastrointestinal tract. Given the interest in using probiotic bacteria in chicken production and the important role of the microbiota in the development and regulation of the host immune system, the objective of the current study was to examine the differential effects of these bacteria on cytokine gene expression profiles of lymphoid tissue cells. Mononuclear cells isolated from cecal tonsils and spleens of chickens were cocultured with one of the three live bacteria, and gene expression was analyzed via real-time quantitative PCR. All three lactobacilli induced significantly more interleukin 1β (IL-1β) expression in spleen cells than in cecal tonsil cells, indicating a more inflammatory response in the spleen than in cecal tonsils. In cecal tonsil cells, substantial differences were found among strains in the capacity to induce IL-12p40, IL-10, IL-18, transforming growth factor β4 (TGF-β4), and gamma interferon (IFN-γ). In conclusion, we demonstrated that L. acidophilus is more effective at inducing T-helper-1 cytokines while L. salivarius induces a more anti-inflammatory response.

In vitro assessment of antimicrobial activity of carvacrol, thymol and cinnamaldehyde towards Salmonella serotype Typhimurium DT104: effects of pig diets and emulsification in hydrocolloids

Aims:  To determine the effect of pig diets in vitro on the antimicrobial activity of carvacrol, thymol and cinnamaldehyde, and to identify an emulsifier/stabilizer that can stabilize the essential oil (EO) components in aqueous solution and retain their antimicrobial activity in the presence of the diets.

Identification of changes in the composition of ileal bacterial microbiota of broiler chickens infected with Clostridium perfringens.

We previously reported that Clostridium perfringens in vivo proliferation and alpha-toxin gene expression were highly correlated, both progressing in a parabolic curve pattern during the development of necrotic enteritis (NE). The present study investigated the response of dominant ileal bacteria in abundance to C. perfringens infection using PCR-based denaturing gradient gel electrophoresis (DGGE) and quantitative PCR (QPCR) techniques. Chickens were fed antibiotic-medicated (bacitracin, 55 mg/kg) or non-medicated diets, and were challenged with C. perfringens through the diet at 18 days of age. Ileal digesta was collected daily before and after the challenge for 5 days. Bacterial profiles of PCR-DGGE from both bacitracin-treated and untreated chickens responding to clostridial infection were analyzed by the principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). Treatment-related differences in PCR-DGGE bacterial profiles on day 2 post-infection (PI) were detected. Subsequent QPCR assays identified changes in the abundance of lactobacilli, L. aviarius in particular. Changes in both populations correlated negatively with the population of C. perfringens in bacitracin-untreated group of chickens that displayed a high incidence of NE lesions. The results indicated that L. aviarius was suppressed by C. perfringens infection. This observation warrants further studies on the mechanisms underlying the ecological change and to assist in further development of novel probiotics to control NE disease.

Quantification of Cell Proliferation and Alpha-Toxin Gene Expression of Clostridium perfringens in the Development of Necrotic Enteritis in Broiler Chickens

ABSTRACT Cell proliferation and alpha-toxin gene expression of Clostridium perfringens in relation to the development of necrotic enteritis (NE) were investigated. Unlike bacitracin-treated chickens, non-bacitracin-treated birds exhibited typical NE symptoms and reduced growth performance. They also demonstrated increased C. perfringens proliferation and alpha-toxin gene expression that were positively correlated and progressed according to the regression model y = b0 + b1X − b2X2. The average C. perfringens count of 5 log10 CFU/g in the ileal digesta appears to be a threshold for developing NE with a lesion score of 2.

Antimicrobial activity of essential oils and structurally related synthetic food additives towards Clostridium perfringens

Aims:  To assess the potential of essential oils and structurally related synthetic food additives in inhibiting the growth of Clostridium perfringens for the control of necrotic enteritis in chickens.

Expression Profiles of Genes in Toll-Like Receptor-Mediated Signaling of Broilers Infected with Clostridium perfringens

ABSTRACT Toll-like receptors (TLRs) participate in detecting microbial pattern molecules for activation of the host immune response. We investigated possible roles of TLRs in the chicken response to Clostridium perfringens infection by examining the expression of TLR genes and other genes involved in TLR-mediated signaling within the spleens and ilea of C. perfringens-challenged broilers. Upregulation of a tumor necrosis factor alpha-inducing factor homolog in challenged chickens compared to naïve chickens was observed, regardless of the incidence of necrotic enteritis. In addition, the members of the TLR2 subfamily were found to be most strongly involved in the host response to C. perfringens challenge, although the expression of TLR4 and TLR7 was also upregulated in spleen tissues. While the combination of TLR1.2, TLR2.1, and TLR15 appeared to play a major role in the splenic response, the expression of TLR2.2 and TLR1.1 was positively correlated to the expression of adaptor molecules MyD88, TRAF6, TRIF, and receptor interacting protein 1 in the ileal tissues, demonstrating a dynamic spatial and temporal innate host response to C. perfringens.

Antimicrobial activity of butyrate glycerides toward Salmonella Typhimurium and Clostridium perfringens

The antimicrobial activities of n-butyric acid and its derivatives against Salmonella Typhimurium and Clostridium perfringens were studied. n-Butyric acid and its derivatives (monobutyrin and a mixture of mono-, di-, and tri-glycerides of butyric acid) were added at different concentrations (ranging from 250 to 7,000 mg/kg to a media inoculated with either Salmonella Typhimurium or C. perfringens. The antimicrobial activity of butyric acid against C. perfringens was measured at 2 bacterium concentrations and 2 inoculations involving ambient aerobic or anaerobic conditions. The most effective antimicrobial activity for Salmonella Typhimurium was observed with n-butyric acid, with 90% inhibition rate at a concentration of 1,500 mg/kg. Although minimal inhibition for Salmonella Typhimurium was observed with butyric acid glycerides, lipase addition to a mixture of mono-, di-, and triglycerides of butyric acid increased (P < 0.01) antimicrobial activity of these derivatives. Antimicrobial activity of butyric acid and its derivative against C. perfringens was higher when using a moderate initial inoculation concentration (10(5)) compared with a higher initial concentration (10(7)) of this bacterium. At a lower inoculation of C. perfringens (10(5)), >90% inhibition rate by all butyric acid glycerides was observed with prior aerobic inoculation at 2,000 mg/kg, whereas using anaerobic inoculation, only 50% monobutyrin maintained >90% inhibitory effect at 3,000 mg/kg. The antimicrobial effect of monobutyrin against C. perfringens was generally higher (P < 0.01) for 50% monobutyrin than for 100% monobutyrin. Either a mixture of butyric acid derivatives or 50% monobutyrin decreased (P < 0.01) C. perfringens in a media containing intestinal contents whereas only 50% monobutyrin decreased (P < 0.01) Salmonella Typhimurium within a media containing cecal contents from mature Leghorns. These results show that n-butyric acid and 50% monobutyrin could be used to control Salmonella Typhimurium or C. perfringens in poultry species.