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Cernat R., Nielsen B.
Chr Hansen A/S, Denmark

The scheduled phase-out of specific antibiotic growth promoters in the EU requires management changes in the pig industry and a need for cost-effective feed additives with high efficacy and thus the need for new probiotics. Bacillus spp.-based feed additives are known for their positive effects on health and production in pigs and are highly relevant for the feed industry since spores are heat stable and can withstand the pelletizing process when temperatures reach up to 90-95 °C.

This work aimed at screening a pool of 260 new spore formers previously isolated from fermented food, healthy pig feces, soil and different culture collections, and selecting the two best candidates for subsequent in vivo trials. One of the two candidates is presented herein. The strain was identified as Bacillus subtilis subsp. subtilis based on 16S rDNA, gyrB and rpoB gene sequencing. Its antibiotic susceptibility was established by minimal inhibitory concentration (MIC) which was found below the accepted breakpoint values. Other analyses included bile and acid tolerance, growth in different media, sporulation and antimicrobial activity against Clostridium perfringens Type A and Type C, Salmonella typhimurium, Staphylococcus aureus and porcine pathogenic E. coli strains belonging to serotypes O147:K89:F4, O149:K91:F4 and O101:K-:F5. In vitro adhesion to porcine jejunal IPEC-J2 cell line, human Caco-2 and mucus-secreting HT-29 MTX cell lines was also investigated. The IPEC-J2 cell line and the porcine pathogenic E. coli strains were further used as in vitro challenged models to assess the probiotic protective effect on small intestinal epithelium. For the in vivo trial, 216 four weeks old newly weaned piglets were randomly allocated to control or Bacillus subtilis (DSM25841) treatment group, respectively, balanced for sex and liveweight. Piglets were fed equal standard diets based on corn, soybean and barley strain or no Bacillus spp.

In vitro adhesion of Bacillus spp. vegetative cells to porcine jejunal IPEC-J2 cells was 12.2 ± 1.93 and comparable to the adhesion to human mucus-secreting HT-29 MTX cells (12.7 ± 0.9) but higher than the adhesion to Caco-2 cells (10.7 ± 1.5). Our data are in agreement with the few similar in vitro studies conducted so far on other probiotic Bacillus spp. and emphasize the ability of our selected candidate to adhere in vitro, and the differences in characteristics and functions exhibited by the three cell lines.
In vitro challenge data showed the protective effect of Bacillus spp. candidate on the porcine IPEC-J2 intestinal cells against the attachment of the porcine pathogenic E.coli. The protective effect proved to be probiotic- and pathogen-specific. Most notably, the in vitro adherence of E.coli O101:K-:F5 decreased significantly (P < 0.05) from 14.1 ± 1.1 to 0.4 ± 0.8 when co-cultivated with Bacillus spp. candidate.
Results showed that feed supplementation with the selected Bacillus spp. DSM 25841 strain had numeric or significant effect on daily gain (235 g/day vs. 218 g/day) and feed conversion (1.15 kg/kg vs. 1.21 kg/kg; P<0.05) as well as improved fecal scoring (P < 0.01) compared to the control group.

Keywords: Swine, Piglets, Gut health, Probiotics, Bacillus spp.

Cernat R., Nielsen B. (2016). New probiotic Bacillus spp. improves gut health in piglets.
Conference Proceedings of IPC2016. Paper presented at the International Scientific Conference on Probiotics and Prebiotics, Budapest (p. 18.). IPC2016

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