The XylR regulatory protein is a transcriptional activator from the TOL plasmid of Pseudomonas putida mt-2 that is involved in the toluene and benzene degradation pathway. Here we describe the construction and laboratory characterization of recombinant biosensors (pGLPX plasmids) based on XylR and its cognate promoter (Pu). In the pGLPX plasmid, the reporter luc gene is under the control of the Pu promoter. We evaluated the ability of two distinct nucleotide sequences to function as SD elements and improve sensitivity of bioreporting. We also evaluated the effect of introducing the T₂rrnβ terminator on the specificity of the construct. E. coli transformed with pGLPX plasmids were used to sense toluene and its derivatives. The pattern of induction was different for each derivative. In general, more luciferase activity was induced by toluene and benzene than by TNT and DNT at most tested concentrations. The bioluminescence response of the reporter strains to the nitrotoluenes was significantly stronger at lower concentrations (≥ 50 μmol) than at higher concentrations. Our results show that the SD sequence (taaggagg) is crucially important for biosensor sensitivity. The presence of the T₂rrnβ terminator in the bioreporter plasmid prevents nonspecific responses and also reduces biosensor sensitivity upon exposure to inducers. These data suggest that pGLPX strains can be used as whole-cell biosensors to detect toluene and related compounds. Further investigation will be required to optimize the application of pGLPX biosensors.

The purpose of the present research is to study the effects of different levels of Aloe vera gel on microflora population, humoral and cellular immune response, and relative weight of lymphoid organs compared to the effects brought about by antibiotic. The groups included the control group (basal diet) as well as three groups with different levels of Aloe vera gel (added to basal diet at 1.5%, 2% and 2.5%), and finally a group with basal diet supplemented by 15 ppm virginiamycin antibiotic. Regarding ileum microflora, the increase in Aloe vera gel in the feed resulted in significant reduction in the number of E. coli colonies and significant increase in the number of Lactobacillus colonies compared to the control and antibiotic groups. As far as humoral immunity is concerned, Newcastle disease virus antibody titre on the 24th and 38th day was the highest in 2.5% and 2% Aloe vera gel groups, respectively. In addition, sheep red blood cells antibody titre reached its highest level in the 2.5% Aloe vera gel group on the days 24, 28, 34 and 38. The differences among the groups regarding sheep red blood cells antibody titre were significant on the days 24, 28 and 34, while no significant differences were observed on the 38th day. Regarding the cellular immunity, the highest response was obtained by injecting phytohemagglutinin-P and the highest relative weight of spleen and bursa of Fabricius was found in the 2.5% Aloe vera gel group. The findings of the study suggest reduction in number of E. coli colonies and increase in number of Lactobacillus colonies as a result of increased Aloe vera gel in the feed. Furthermore, the 2.5% Aloe vera gel group resulted in significantly higher levels of humoral and cellular immunity, as well as relatively greater weight of lymphoid organs, which suggests that Aloe vera gel can be a proper replacement for the virginiamycin antibiotic.

1. The objective of present study was to evaluate the effects of intra-amniotic injection of different probiotic strains (Bacillus subtilis, Enterococcus faecium and Pediococcus acidilactici) on the intestinal MUC2 gene expression, microbial population, growth performance and immune response in broiler chicken. 2. In a completely randomised design, different probiotic strains were injected into the amniotic fluid of the 480 live embryos (d 18 of incubation), with 4 treatments and 5 replicates. Ileal MUC2 gene expression, microbial profile, growth performance and immune response were determined. 3. Injection of probiotic strains, especially B. subtilis, had significant effect on expression of the MUC2 on d 21 of incubation and d 3 post-hatch, but not on d 19 of incubation. 4. Injection of the probiotic strains decreased significantly the Escherichia coli population and increased the lactic acid bacteria population during the first week post-hatch. 5. Inoculation of probiotics had no significant effect on antibody titres against Newcastle disease virus, antibody titres against sheep red blood cell and cell-mediated immune response of chickens compared to control. 6. In ovo injection of the probiotic strains had no significant effect on growth performance of broiler chickens. 7. It was concluded that injection of probiotic bacteria especially B. subtilis into the amniotic fluid has a beneficial effect on ileal MUC2 gene expression and bacteria population during the first week post-hatch, but has no effect on growth performance and immune response in broiler chickens.

The present study attempts to analyze the effects of different levels of Aloe vera gel as an alternative to antibiotic, on performance and ileum morphology in broilers. Three hundred one-day old Ross 308 male broilers were used on a completely randomized design in 5 groups with 4 replicates, each consisting of 15 broilers. The groups included the control group (basal diet) and three groups with basal diet mixed with different levels of Aloe vera gel (1.5%, 2% and 2.5%). Finally, there was a group with basal diet plus 15 ppm antibiotic virginiamycin. The results obtained regarding performance of the broilers showed that Aloe vera gel groups brought about higher body weight gain and feed intake compared to the control group; however, no significant difference was observed in feed conversion ratio between the groups treated by Aloe vera gel and the control group (P>0.05). Although the antibiotic group showed better performance and heavier dressing percentage than the Aloe vera gel and the control groups, no significant difference was seen between the group treated by 2% Aloe vera gel and the antibiotic group regarding body weight gain, feed conversion ratio and dressing percentage (P>0.05). Among the Aloe vera gel groups, the 2% Aloe vera gel group had the largest villus height and the greatest villus height to crypt depth ratio compared to the antibiotic group (P<0.05). In general, 2% Aloe vera gel treatment may be recommended to achieve the best performance in broilers as an alternative to antibiotic growth promoter.

A total of 360 fertile eggs from a broiler breeder strain (Ross 308) were used for in ovo feeding (IOF) of 0, 100 and 200 mg/kg Silybum marianum water extract at 17.5 d of incubation. After hatching, 240 chicks were transferred to the experimental cages. The diets consisted of two types; one of them without extract and the other one containing 100 mg/kg of Silybum marianum extract. Then chicks were exposed to elevated temperatures 4°C above optimum from 7 to 28 d of age for 4 h per d and after 28 d they were kept at optimum temperature. The chicks were divided into 6 treatments with 4 replicates as a completely randomised 2 × 3 factorial design. There was no effect of IOF of Silybum marianum extract on hatchability, body weight (BW) of hatched chicks or hatched chick BW/initial egg weight ratio. Chickens fed on the diet containing the extract had the highest feed intake, daily weight gains (DWGs), final BW and lowest feed conversion ratio. At 28 d, the weights of heart, spleen and bursa of birds in the treatment groups given extract were higher, but abdominal fat weights were lower. At 42 d in those fed extract in the diet, the weights of spleen and bursa were higher and abdominal fat weights were lower than the other groups. No differences were observed between groups in body temperature before application of the higher temperature but at 21 d and 28 d the body temperature of chicks given the Silybum marianum extract was lower than the other treatments during the elevated temperatures. In birds fed on the extract in the diet, HDL and cholesterol concentrations were lowest at 28 d, whereas blood glucose levels were higher in the other treatments. At 42 d the cholesterol concentration was significantly lower in birds given extract in their diet. These results indicated that dietary feeding of Silybum marianum extract resulted in an improvement in performance, immunity and carcass characteristics and decreased the adverse effects of the higher temperatures, specifically in reducing blood fat reduction, but IOF of the extract did not have an effect.

A study was conducted to examine how supplementation using probiotics and whey powder affects microflora population, ileum morphology, and growth performance in broilers. In this experiment, 400 one-day-old male chickens were randomly assigned into four groups: the control group (CON), the probiotics group (0.2%) (PRO), the whey powder group (4%) (WHP), and a group that received a combination of probiotics (0.2%) and whey powder (4%) (PRO-WHP). Microflora populations as well as ileum morphology were assessed on day 42 and growth performance parameters were measured at the end of the rearing period (day 42). The findings indicated that the PRO-WHP group had the largest Lactobacillus count (P < .05) while the lowest Escherichia coli count was found in the WHP. No significant difference was found between the PRO group and the WHP (P > .05) for villus:crypt ratio. The largest feed intake and body weight gain were observed in the PRO-WHP group. In addition, the PRO-WHP group had the best feed conversion ratio, but was not significantly different from the PRO and the WHP groups. Our experiment indicated that adding whey powder alone or in combination with probiotics can improve broiler performance by modifying intestinal microflora and changing intestinal morphology.

The objective of the present study was to evaluate the effects of in ovo infusion of probiotic strains (Bacillus subtilis, Enterococcus faecium, and Pediococcus acidilactici) on jejunal microbial population and mucin gene expression in broiler chicken. In a completely randomized design, 0.5 ml of mediums containing 10 7 cfu of different probiotic strains, was administered into amniotic fluid of the 480 Cobb fetus (day 18 of incubation), with four treatments, five replicates with twenty four eggs each. For mucin gene expression, samples from the jejunum were taken on day 21 of incubation and day 3 post-hatch. Microbial profile was determined for total lactobacillus and E. coli by sampling jejunal contents on days 1 and 3 of age. Expression of the mucin gene in the jejunum was higher (p<0.05) in chicks that received Bacillus subtilis in comparison with the control group. Infusion of the probiotic strains had no effect on jejunal E. coli and lactic acid bacteria populations on day 1 post-hatch (p>0.05). There were no significant differences among treatments for performance parameters at different periods and the whole period. It was concluded that infusion of probiotic bacteria during the late of incubation has no effect on feed intake, gain and feed conversion ratio, but has a positive effect on mucin gene expression in the jejunum. The best probiotic strain for mucin gene expression was Bacillus subtilis and for beneficiary bacteria colonization was Bacillus subtilis and Pediococcus acidilactici.

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