Development of an in vitro Model of Probiotic Adherence and Colonization for Poultry

Probiotics are live microorganisms which when consumed in adequate amounts confer a health benefit upon the host. Commonly associated with the gastrointestinal tract of warm blooded animals, Lactobacillus species are often used as probiotics. Benefits of probiotic Lactobacillus use include improved digestive health, immune modulation, and increased resistance to enteric pathogens. Benefits of probiotic administration to poultry production include improved performance and feed conversion, reduced mortality, and improved food safety due to reduced colonization by human foodborne pathogens.

Adherence to intestinal epithelia and persistence in the gastrointestinal tract is antecedent to the realization of benefits of probiotic lactobacilli. Lactobacillus species produce proteins, including fibronectin binding proteins, mucus binding proteins, and surface layer proteins, that associate with host factors and are responsible for bacterial adhesion. In vitro assays based on stable cell lines have been used to investigate adherence of Lactobacillus to epithelial cells. However, there have been no studies using poultry derived epithelial cell lines. In this study, we have developed an assay based on the chicken LMH epithelial cell line to investigate adherence and colonization of Lactobacillus species in poultry. Adherence assays revealed Lactobacillus crispatus ST1, Lactobacillus crispatus JCM 5810, Lactobacillus gallinarum ATCC 33199, and Lactobacillus gallinarum JCM 8782 were able to effectively adhere to the chicken LMH cell line when compared to low-adherent Bacillus subtilis and high-adherent Salmonella controls. Administration of these rifampicin resistant variants of these Lactobacillus cultures to broiler chicks revealed these cultures to transiently colonize the gastrointestinal tract. L. crispatus ST1 and L. gallinarum ATCC 33199 were found to persist more effectively than L. crispatus JCM 5810 and L. gallinarum JCM 8782. These studies of the adherence and colonization of poultry by Lactobacillus cultures are expected to contribute to improved understanding of the functionality of these microorganisms in poultry production.