Probiotic Lactobacilli Do Not Protect Chickens against Salmonella Enteritidis Infection by Competitive Exclusion in the Intestinal Tract but in Feed, Outside the Chicken Host

Abstract

Lactobacilli are commonly used as probiotics in poultry to improve production parameters and to increase chicken resistance to enteric infections. However, lactobacilli do not efficiently colonise the chicken intestinal tract, and also, their anti-infection effect in vivo is sometimes questionable. In this study, we therefore evaluated the potential of a mixture of four Lactobacillus species (L. salivarius, L. reuteri, L. ingluviei and L. alvi) for the protection of chickens against Salmonella Enteritidis infection. Whenever the chickens were inoculated by lactobacilli and S. Enteritidis separately, there was no protective effect of lactobacilli. This means that when lactobacilli and S. Enteritidis are exposed to each other as late as in the crop of chickens, lactobacilli did not influence chicken resistance to S. Enteritidis at all. The only positive effect was recorded when the mixture of lactobacilli and S. Enteritidis was used for the inoculation of feed and the feed was anaerobically fermented for 1 to 5 days. In this case, chickens fed such a diet remained S. Enteritidis negative. In vitro experiments showed that the protective effect was caused by acidification of feed down to pH 4.6 due to lactobacilli fermentation and was associated with S. Enteritidis inactivation. The probiotic effect of lactobacilli was thus expressed in the feed, outside the chicken host.

Live Performance and Microbial Load Modulation of Broilers Fed a Direct-Fed Microbials (DFM) and Xylanase Combination

“…It can be classified as an opportunistic pathogen that would take advantage of damaged epithelial cell wall to exert its effect. Promoting healthy gut microflora, as well as reducing litter moisture, could aid in minimizing favorable conditions for C. perfringens to express its virulency [ 51 , 52 , 53 , 54 ].…”

Colonization of chickens with competitive exclusion products results in extensive differences in metabolite composition in cecal digesta

“…Unfortunately, Bacillus does not represent a common gut microbiota member in chickens and Lactobacillus strains are present in gut microbiota of chickens from the first days of their life ( Videnska et al, 2014 ). Their additional administration is therefore of questionable value, especially when it is known that lactobacilli colonize the chicken intestinal tract poorly ( Kubasova et al, 2019b ; Juricova et al, 2022 ), which makes linking their administration with the metabolic profile rather complicated. Previous studies used broilers, that is, chickens with underdeveloped gut microbiota.…”

Microbial Succession in the Cheese Ripening Process—Competition of the Starter Cultures and the Microbiota of the Cheese Plant Environment

“…Their main function is fermentation, i.e., the conversion of available sugars into lactic acid. The desirable side effect of this enzymatic process is the acidification of the product, and thus the formation of an additional barrier inhibiting spoilage flora and pathogens [ 1 , 2 ]. In the next step, yeast cultures are often applied to the cheese to raise the pH by metabolizing lactate on the cheese surface, thereby promoting the growth of adjunct cultures and other acid-sensitive microbiota [ 3 , 4 ].…”