It was hypothesized that dietary inclusion of Bacillus subtilis DSM 32315 could inhibit Clostridium perfringens induced necrotic enteritis (NE), thereby improving broiler performance. Male, d 0 chicks were randomly assigned 14 birds/pen, 11 pens/treatment in 3 treatments: a basal diet (control), a coccidiostat fed control (Narasin), and a direct fed microbial (DFM) B. subtilis DSM 32315 treatment. Necrotic enteritis was induced in all birds by oral inoculation of Eimeria maxima oocysts on d 12 and a virulent C. perfringens on d 16. Mortality was reduced ( P < 0.001) in DFM and Narasin compared to control. DFM reduced ( P < 0.001) feed conversion ratio (FCR) compared to control. Furthermore, DFM and Narasin reduced ( P < 0.001) footpad lesions. The DFM was shown to increase ( P < 0.05) Bacillus spp. and decrease ( P < 0.05) C. perfringens in the ileum and cecum at several time points. To investigate microbiome changes in the cecum, digesta samples were analyzed with % guanine and cytosine (%G+C) microbial profiling which fractionates bacterial chromosomes based on the %G+C in DNA. The method revealed treatment profile peaks in low (27.0 to 34.5%), mid (40.5 to 54.0%), and high (59.0 to 68.0%) G+C fractions. 16S rRNA gene amplification and high throughput sequencing was conducted on each of these fractions in order to elucidate specific bacterial population differences. In the low and mid %G+C fractions, DFM had greater abundance of Lactobacillaceae family members ( P = 0.03 and P = 0.01, respectively) and Lactobacillus salivarius ( P = 0.04 and P = 0.01, respectively) than control or Narasin. Lactobacillus johnsonii was also greater in the low %G+C fraction compared to control and Narasin ( P = 0.01). Lachnospiraceae ( P = 0.04) and Ruminococcaceae ( P < 0.01) in the mid %G+C fraction were reduced in the DFM compared to control. Positive alterations to the microbial populations in the gut of broilers may at least be a partial mechanism by which B. subtilis DSM 32315 reduced pathology and improved performance of broilers in the NE challenge.

New treatment strategies for inflammatory bowel disease are needed and parasitic nematode infections or application of helminth components improve clinical and experimental gut inflammation. We genetically modified the probiotic bacterium Escherichia coli Nissle 1917 to secrete the powerful nematode immunomodulator cystatin in the gut. This treatment was tested in a murine colitis model and on post-weaning intestinal inflammation in pigs, an outbred model with a gastrointestinal system similar to humans. Application of the transgenic probiotic significantly decreased intestinal inflammation in murine acute colitis, associated with increased frequencies of Foxp3(+) Tregs, suppressed local interleukin (IL)-6 and IL-17A production, decreased macrophage inflammatory protein-1α/β, monocyte chemoattractant protein -1/3, and regulated upon activation, normal T-cell expressed, and secreted expression and fewer inflammatory macrophages in the colon. High dosages of the transgenic probiotic were well tolerated by post-weaning piglets. Despite being recognized by T cells, secreted cystatin did not lead to changes in cytokine expression or macrophage activation in the colon. However, colon transepithelial resistance and barrier function were significantly improved in pigs receiving the transgenic probotic and post-weaning colon inflammation was reduced. Thus, the anti-inflammatory efficiency of a probiotic can be improved by a nematode-derived immunoregulatory transgene. This treatment regimen should be further investigated as a potential therapeutic option for inflammatory bowel disease.

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Background Previous research has shown that dietary supplementation of Bacillus spp. probiotics exerts beneficial effects on animals’ growth. However, limited studies have evaluated the efficacy of Bacillus spp. on weaned pigs and their effects on host gut health and microbiome, and systemic immunity using a disease challenge model. The objective of this experiment was to investigate the effects of two Bacillus spp. strains (Bacillus subtilis DSM 32540 and Bacillus pumilus DSM 32539) on growth performance, diarrhea, intestinal health, microbiome, and systemic immunity of weaned pigs experimentally infected with an enterotoxigenic Escherichia coli (ETEC). Results Pigs in PRO1 (Bacillus subtilis DSM 32540) had greater (P < 0.05) body weight on d 7 and 14 PI, greater (P < 0.05) ADG from d 0 to 7 and d 7 to 14 PI, compared with pigs in CON (Control). Pigs in PRO1 had milder (P < 0.05) diarrhea on d 2 and 3 PI compared with pigs in CON. However, no differences were observed in growth performance and diarrhea score between PRO2 (Bacillus pumilus DSM 32539) and CON groups. Supplementation of PRO1 decreased (P < 0.05) lymphocyte counts on d 7 and 14 PI, compared with CON. Supplementation of PRO1 and PRO2 both reduced (P < 0.05) total coliforms in mesenteric lymph nodes on d 21 PI. Pigs in PRO2 had greater (P < 0.05) goblet cell number and sulfomucin percentage in duodenal villi and greater (P < 0.05) sialomucin percentage in jejunal villi than pigs in CON. Supplementation of PRO1 up-regulated (P < 0.05) MUC2 gene expression in jejunal mucosa and reduced (P < 0.05) PTGS-2 and IL1B gene expression in ileal mucosa on d 21 PI, compared with CON. Pigs in PRO1 had reduced (P < 0.05) relative abundance of families Lachnospiraceae, Peptostreptococcaceae and Pasteurellaceae in the ileum. Conclusions Supplementation of Bacillus subtilis DSM 32540 improved growth performance, alleviated diarrhea severity, enhanced gut health, and reduced systemic inflammation of weaned pigs infected with ETEC F18. Although Bacillus pumilus DSM 32539 was able to alleviate systemic inflammation, it had limited impacts on growth performance and severity of diarrhea of ETEC F18 challenged weaned pigs.

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