Research Note: The effects of a Lactobacillus helveticus ATCC 15009-derived postbiotic mitigating Salmonella Gallinarum colonization in commercial layer chicks.

This study aimed to assess the effects of a Lactobacillus helveticus ATCC 15009-derived postbiotic in mitigating experimental Salmonella Gallinarum infection. For this purpose, a sample of Lactobacillus sp. was inoculated in 2 different media, each containing different postbiotics (sensitized and nonsensitized). Both inocula had their antagonistic effect over S. Gallinarum tested through the spot-on-the-lawn method. It revealed that the sensitized postbiotic had a higher action potential over Lactobacillus sp. than the nonsensitized one (P < 0.05). Then, 48 day of hatch chicks were divided into 4 groups: A = Lactobacillus sp. (109 CFU/mL) inoculum on the 18th day; B = Lactobacillus sp. (109 CFU/mL) inoculum on the 18th day and postbiotic inoculum on the 19th day; C = postbiotic inoculum on the 19th day; and D = sterile saline inoculum on 18th and 19th days. On the 21st day, all chicks were infected with S. Gallinarum (109 CFU/mL). On the 23rd day, the animals were euthanized by cervical dislocation, and the ceca and liver were aseptically removed. Bacterial count of S. Gallinarum with serial decimal dilution was performed with these organs. It revealed that the prophylactic treatment with the postbiotic that modulates the intestinal microbiota was as efficient as the probiotic administration in reducing S. Gallinarum in the cecum and liver of chicks (P < 0.05). These data point to a new range of alternatives for preventing S. Gallinarum, which might help the poultry industry produce safer food for human consumption.

Bacterial communication between Lactobacillus spp. isolated from poultry in the inhibition of Salmonella Heidelberg-proof of concept.

Bacterial communication has become an increasingly studied topic aiming at the discovery of new products to aid the treatment of diseases for which conventional options do not work. The production of safe foods, free of pathogens, has been receiving increasing attention due to market demands for food products of high quality and free of residues. This study assessed the communication between Lactobacillus spp. during the in vitro inhibition of Salmonella Heidelberg (SH) and the impact an autoinducer produced by a strain of Lactobacillus plantarum has on communication in the normal microbiota and inhibiting SH in newborn chicks. For this purpose, the isolates of Lactobacillus spp. were isolated cloacal swabs of broilers and identified through biochemical and molecular assays and were obtained from broiler farms. They later had their inhibitory potential against SH stimulated after contact with the autoinducer. For assessing bacterial communication (quorum sensing) during the inhibition of SH by Lactobacillus spp., a spot on the lawn assay was conducted. For the in vivo, 75 one-day-old chicks were divided in 5 experimental groups: control with no treatment; treatment with a Lactobacillus spp. pool on the first day; treatment with autoinducer on the second day; treatment with Lactobacillus spp. on the first day; and autoinducer on the second day and treatment without autoinducer. The autoinducer was assessed through an SH count in the ceca of the birds. The autoinducer produced by the strain of L. plantarum proved to be efficient for communicating with the other Lactobacillus spp. isolates as previous contact with SH induced the production of an autoinducer capable of increasing inhibition of SH both in vitro (in average 132.73%) and in vivo, acting similarly to the Lactobacillus spp. pool (probiotic) by decreasing the SH count in the ceca (64%-24 h, 42%-96 h, and 46%-168 h).