Devillard E., Nelson A., Brinch K., Rayat L., Nielsen P.
Novozymes, Denmark

Gut health is a major factor to be taken into consideration for the optimum performance of birds. In all animal species, it is becoming increasingly clear that intestinal microbiota mediates key physiological processes thereby influencing the host. Probiotics can positively impact these processes, however their effects are strain dependent. In the present study, we describe a novel strain of Bacillus subtilis that was phylogenetically different from commonly applied Bacillus strain. It was found to have specific impact on animal performance, gut microbiota and host intestinal functions.

A novel strain of Bacillus subtilis was identified by comparisons of whole genome sequences. To study the phylogeny of the selected strain (B. subtilis DSM29784), a comparative analysis of the gyrB gene sequences was performed using about 1200 nt partial gyrB gene sequences.
Animal trials were conducted in three different trial facilities to assess the impact of strain DSMZ29784 on broiler performance. Broilers were fed 1.0E8CFU/kg feed and Feed conversion was measured at day 28 and 42. Furthermore, samples from a 42-day in vivo performance study in broilers were used for assessment of effects on epithelial cells and gut response. Samples from the small intestine were examined by electron microscopy to measure gut morphology and microvillus length comparing untreated controls to animals receiving DSM29784. The changes in microbiota in cecum were assessed by Illumina MiSeq.

The gyrB gene analysis suggests that DSM29784 is a novel subspecies of B. subtilis.
In vivo results showed a significant improvement in animal performance in all three animal studies when compared to negative controls with an average FCR improvement of 3.8% at day 35 (p<0.05) when compared to untreated controls.
In the 42 day study FCR improved by 5.7%, (p<0.05) when compared to untreated controls of broilers. Samples from the small intestine showed significantly longer microvilli (p<0.0001) in treated (0.8 um) compared to untreated (0.68 um) animals. Treatment with DSM29784 also resulted in changes in the cecal microbiota with increase in butyrate producing species such as Ruminococcus (increased from 1.6 to 5.1%).

Bacillus subtilis is a bacterial species that covers quite extensive diversity. As a consequence the species have currently been divided into three subspecies B. subtilis subsp. subtilis, spizizenii and inaquosorum. The phylogenetic studies suggest that the Bacillus subtilis DSM29784 belongs to a new fourth subspecies.
This novel strain was tested in animal studies. The results of these in vivo tests showed significant improvement in animal performance which was found to be linked to the strain’s impact on the host microbiota and host epithelial wall. These data support that the effects of probiotic bacteria are strain specific and that a probiotic strain with certain specific properties can benefit the health and growth of commercial broilers.

Keywords: Probiotics, Microbiota, Animal performance, Novel Bacillus subtilis, Host response

Devillard E., et al. (2016). Novel Bacillus subtilis strain brings health benefits and improvement of performance in broilers. Conference Proceedings of IPC2016. Paper presented at the International Scientific Conference on Probiotics and Prebiotics, Budapest (p. 22.). IPC2016

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