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Simple Summary: Postweaning diarrhea due to pathogenic Escherichia coli is a common issue in swine production. Specific strains of Bacillus subtilis have been shown to reduce the incidence and severity of diarrhea and thereby improve the growth of nursery pigs. The current study aims to demonstrate the effect of B. subtilis supplementation of two strains selected to reduce the effects of pathogenic E. coli to nursery pig diets on growth performance, blood biochemicals, fecal metabolites, and microbiome. B. subtilis supplementation to nursery diets at 1.875 × 105 CFU/g diet improved early postweaning growth performance, increased blood glucose levels, and fecal short-chain fatty acid production, which is beneficial for the gut health and development for nursery pigs. But a higher dose of B. subtilis did not affect pig growth and fecal short-chain fatty acid production. These results suggest that B. subtilis supplementation to nursery pig diets at 1.875 × 105 CFU/g diet is beneficial for growth and gut health, whereas a higher dose of the probiotic may not be as effective as the recommended level. This experiment was conducted to evaluate the effects of dietary supplementation level of a two-strain Bacillus subtilis probiotic on growth performance, blood parameters, fecal metabolites, and microbiome in nursery pigs. A total of 54 weaned piglets were allotted to three treatments in three replicate pens with six pigs/pen for a 28 d feeding trial. The treatments were as follows: control: no probiotic supplementation; Pro1x: B. subtilis supplementation at 1.875 × 105 CFU/g diet; and Pro10x: B. subtilis supplementation at 1.875 × 106 CFU/g diet. Body weight at d 14 postweaning (p = 0.06) and average daily gain for d 0 to 14 postweaning (p < 0.05) were greater in the Pro1x treatment than in the other treatments. Blood glucose levels were greater in both probiotic treatments than in the control treatment at d 14 postweaning (p < 0.05). In the fecal short-chain fatty acid (SCFA) concentrations, the butyrate concentrations were greater in the Pro1x treatment than in the other treatments (p < 0.05), and the acetate, propionate, and total SCFA concentrations were greater in the Pro1x treatment than in the Pro10x treatment (p < 0.05). The beta diversity of fecal microbiome composition at d 14 postweaning based on Unweighted Unifrac analysis was dissimilar between the Pro1x and Pro10x treatments (p < 0.05). In conclusion, dietary B. subtilis supplementation of two strains selected to reduce effects of pathogenic Escherichia coli to nursery diets at 1.875 × 105 CFU/g diet improved the growth rate in the early postweaning period, increased fecal SCFA concentrations and altered the fecal microbial community composition. A higher dose of B. subtilis did not improve the performance parameters over those of the control piglets. [ABSTRACT FROM AUTHOR]

The first application of the isopropyl-[beta]-D-thiogalactopyranoside (IPTG)-inducible lac repressor/operator system to Borrelia burgdorferi genetics which could be also be used to assess the regulation of other genes potentially involved in virulence expression by Borrelia burgdorferi is demonstrated.

The alternative sigma factor (RpoN-RpoS) pathway controls the expression of key virulence factors in Borrelia burgdorferi. However, evidence to support whether RpoN controls rpoS directly or, perhaps, indirectly via a transactivator has been lacking. Herein we provide biochemical and genetic evidence that RpoN directly controls rpoS in B. burgdorferi.

This experiment was conducted to evaluate the effects of dietary supplementation level of probiotics on growth performance, blood variables, and fecal metabolites in nursery pigs. Certain strains of Bacillus subtilis have been shown to reduce the incidence and severity of diarrhea and therefore improve growth performance of nursery pigs. A total of 54 newly weaned piglets were allotted to 3 treatments in 3 replicates with 6 pigs per pen based on body weight, gender, and breed for a 28-d feeding trial. Treatments were: 1) Control: no probiotics supplementation, 2) CERTILLUS 1x: probiotics supplementation at the recommended level, and 3) CERTILLUS 10x: probiotics supplementation at 10 times the recommended level. The CERTILLUS products consisted of two strains of Bacillus subtilis at a low and a high dose of 3.75 × 108 CFU/g and 3.75 × 109 CFU/g supplemented at 0.05% resulting in 1.875 × 105 CFU/g diet and 1.875 × 106 CFU/g diet for the 1x and 10x treatments, respectively. Corn-soybean meal-based diets were used for d 0-14 (Phase 1) and d 14-28 (Phase 2) postweaning. Body weight, blood glucose and creatinine, fecal short chain fatty acid (SCFA) and bile acid concentrations were measured at d 14 and 28 postweaning. Body weight at d 14 postweaning (P = 0.06; 11.98, 12.73, and 12.21 kg for the control, 1x, and 10x treatments, respectively) and average daily gain for d 0 to 14 postweaning (P < 0.05; 0.206, 0.259, and 0.222 kg/d, respectively) were greater in the 1x treatment than the control and 10x treatments although there was no significant difference in growth performance at d 28 postweaning. Blood glucose concentrations were greater in both probiotic treatments than the control treatment at d 14 postweaning (P < 0.05; 95.2, 111.7 and 114.3 mg/dL for the control, 1x, and 10x treatments, respectively). In the fecal SCFA concentrations, the butyrate concentrations were greater in the 1x treatment than the control and 10x treatments (P < 0.05; 36.17, 47.57, and 33.23 µmol/g feces for the control, 1x, and 10x treatments, respectively) and the acetate (120.02, 141.87, and 101.17 μmol/g feces, respectively), propionate (62.95, 71.42 and 55.27 µmol/g feces, respectively), and total SCFA (236.72, 282.23, and 205.80 µmol/g feces, respectively) concentrations were greater in the 1x treatment than the 10x treatment with the intermediate value in the control treatment (P < 0.05). There were no significant differences in fecal bile acid concentrations and blood creatinine concentrations at both d 14 and 28 postweaning. In conclusion, dietary probiotics supplementation to nursery diets at the recommended level could improve growth rate in the early postweaning period and increase fecal SCFA concentrations but not at a high level of supplementation. [ABSTRACT FROM AUTHOR]

The gene expression profiles of Escherichia coli strains grown anaerobically with or without Acacia mearnsii extract are compared in order to identify tannin resistance strategies. The studies have shown that BaeSR mutants are more tannin sensitive than their wild-type counterparts.

Research has been conducted on tannins, polyphenols with antimicrobial effects. The study of the tannin toxicity mechanism toward Escherichia coli has been carried out via the use of Acacia mearnsii extract as a condensed tannin source, and the details are reported.

A quantitative PCR (qPCR) assay targeting a gene identified by suppressive subtractive hybridization (SSH) was developed to detect Propionibacterium acidipropionici P169, with a threshold of 104 CFU/U of dairy feed or rumen fluid. The report is the first using a molecular marker generated by SSH to quantify a bacterial strain in environmental samples. [ABSTRACT FROM AUTHOR]

The gene expression profiles of Escherichia coli strains grown anaerobically with or without Acacia mearnsii (black wattle) extract were compared to identify tannin resistance strategies. The cell envelope stress protein gene spy and the multidrug transporter-encoding operon mdtABCD, both under the control of the BaeSR two-component regulatory system, were significantly up-regulated in the presence of tannins. BaeSR mutants were more tannin sensitive than their wild-type counterparts. [ABSTRACT FROM AUTHOR]

The alternative sigma factor (RpoN-RpoS) pathway controls the expression of key virulence factors in Borrelia burgdorferi. However, evidence to support whether RpoN controls rpoS directly or, perhaps, indirectly via a transactivator has been lacking. Herein we provide biochemical and genetic evidence that RpoN directly controls rpoS in B. burgdorferi. [ABSTRACT FROM AUTHOR]