In vitro characteristics of Lactobacillus spp. strains isolated from the chicken digestive tract and their role in the inhibition of Campylobacter colonization

Campylobacter jejuni/coli infections are the leading cause of bacterial diarrheal illnesses in humans. Many epidemiological studies indicate that improperly prepared meat from chickens that carry a high load of Campylobacter in their intestinal tracts is the key source of human infections. LAB, mainly members of the Lactococcus and Lactobacillus genera, increasingly have been tested as vehicles for the delivery of heterologous bacterial or viral antigens to animal mucosal immune systems. Thus, the objective of this study was to isolate, identify, and characterize Lactobacillus spp. strains isolated from chickens bred in Poland. Their ability to decrease the level of bird gut colonization by C. jejuni strain was also analyzed. First, the influence of the different chicken rearing systems was evaluated, especially the effect of diets on the Lactobacillus species that colonize the gut of chickens. Next, selected strains were analyzed in terms of their anti-Campylobacter activity in vitro; potential probiotic traits such as adhesion properties, bile and low pH tolerance; and their ability to grow on a defined carbon source. Given that improperly prepared chicken meat is the main source of human infection by Campylobacter, the selected strains were also assessed for their ability to inhibit Campylobacter colonization in the bird's intestine. These experiments revealed enormous physiological diversity among the Lactobacillus genus strains. Altogether, our results showed that L. plantarum strains isolated from the digestive tracts of chickens bred in Poland displayed some probiotic attributes in vitro and were able to decrease the level of bird gut colonization by C. jejuni strain. This suggests that they can be employed as vectors to deliver Campylobacter immunodominant proteins to the bird's immune system to strengthen the efficacy of in ovo vaccination.