Date of Completion

2025

Document Type

Thesis

Degree Name

Bachelor of Science in Life and Health Sciences

Keywords

Shouchella clausii, Salmonella typhimurium, in vitro, probiotic, Salmonella infection, competitive exclusion, chicken cecum

Abstract

The increasing prevalence of Salmonella infections in poultry presents serious concerns for food safety and public health, especially amid rising antimicrobial resistance (AMR). This has led to an increasing interest in probiotic-based interventions as alternatives to antibiotics in poultry production. This study was conducted to evaluate the competitive exclusion potential of Shouchella clausii, a spore-forming probiotic, in inhibiting the growth of S. typhimurium under simulated in vitro chicken cecum conditions. Given the limited research on the use of S. clausii in poultry applications, this study aimed to explore its viability as a non-antibiotic strategy for S. typhimurium control. Specifically, this study aimed to (1) simulate an in vitro environment that mimicks the physiological conditions of the chicken cecum, including pH, temperature, and bile concentration; (2) quantify S. typhimurium growth through counting of CFU/mL; and (3) assess the inhibitory effect of S. clausii on S. typhimurium via statistical comparison of treatment groups. Results showed that the group co-inoculated with S. clausii (CT group) consistently exhibited lower CFU/mL values of S. typhimurium compared to the Salmonella-only group (ST group), with values ranging from 2.1 × 10⁻³ to 6.6 × 10⁻³ CFU/mL in the CT group versus 2.2 × 10⁻³ to 1.88 × 10⁻² in the ST group. However, Welch’s t-test indicated no statistically significant difference (p = 0.1701) at 5% level of significance. The short 24-hour incubation period and limited sample size may have constrained the ability to detect meaningful differences. In conclusion, S. clausii demonstrated a lower mean CFU/mL of S. typhimurium compared to the Salmonella-only group, suggesting its potential as a probiotic candidate. Further in vivo studies and extended incubation trials are recommended to validate its efficacy under real poultry conditions.

First Advisor

April B. Ambita, MSc

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