Veterinary session

Modern farming continues to intensify with much higher demands for production animals.

Consequently, the crowding and stress associated with intensive farming practices inherent in large-scale swine production yield a high incidence of intestinal infections caused by Escherichia coli (E. coli) and Salmonella enterica serovar Typhimurium (S. Typhimurium).

These pathogens can induce oxidative stress and compromise the intestinal barrier function, resulting in diminished production, the emergence of clinical symptoms, or even mortality.

For many years now, the habitual use of antibiotics for disease prevention and growth enhancement has played a significant role in the emergence and escalation of antimicrobial resistance. Currently the European Union is enforcing strict regulations on the use of antibiotics in veterinary medicine, especially on food producing animals. This has given rise to a demand for alternative treatments and dietary supplements that shall not result in resistance but positively impact animal health and productivity while preserving the integrity of the intestinal barrier.

In our experiments, we explored the efficacy of the protective actions of the probiotic bacterium Bacillus licheniformis (B. licheniformis) on intestinal porcine epithelial (IPEC-J2) cells when challenged with the pathogenic strains of E. coli and S. Typhimurium bacteria.

Firstly, by means of the Neutral Red assay, we ascertained that at a concentration of (10^8) CFU/mL, B. licheniformis did not impact the viability of IPEC-J2 cells; this concentration was thus employed in proceeding experiments. Subsequently, the DCFH-DA assay was used to examine the intracellular redox state of the cells. In this phase, B. licheniformis and the pathogenic bacteria were introduced to the cells in three distinct treatment modalities: pre-treatment, co- treatment, and post-treatment.

Lastly, we evaluated the preventative efficacy of B. licheniformis in regards to inhibition of adhesion of pathogenic bacteria to the IPEC-J2 intestinal epithelial cells.

Our study's findings reveal that B. licheniformis significantly mitigates the oxidative stress triggered by E. coli and S. Typhimurium in porcine intestinal epithelial cells. Moreover, this probiotic curtails the adhesion of pathogenic bacteria. It appears that B. licheniformis is a strong contender for contribution to the positive effects of probiotics in animal health.