Recent Advances in Screening of Anti-Campylobacter Activity in Probiotics for Use in Poultry.

Campylobacteriosis is the most common cause of bacterial gastroenteritis worldwide. Campylobacter species involved in this infection usually include the thermotolerant species Campylobacter jejuni. The major reservoir for C. jejuni leading to human infections is commercial broiler chickens. Poultry flocks are frequently colonized by C. jejuni without any apparent symptoms. Risk assessment analyses have identified the handling and consumption of poultry meat as one of the most important sources of human campylobacteriosis, so elimination of Campylobacter in the poultry reservoir is a crucial step in the control of this foodborne infection. To date, the use of probiotics has demonstrated promising results to reduce Campylobacter colonization. This review provides recent insights into methods used for probiotic screening to reduce the prevalence and colonization of Campylobacter at the farm level. Different eukaryotic epithelial cell lines are employed to screen probiotics with an anti-Campylobacter activity and yield useful information about the inhibition mechanism involved. These in vitro virulence models involve only human intestinal or cervical cell lines whereas the use of avian cell lines could be a preliminary step to investigate mechanisms of C. jejuni colonization in poultry in the presence of probiotics. In addition, in vivo trials to evaluate the effect of probiotics on Campylobacter colonization are conducted, taking into account the complexity introduced by the host, the feed, and the microbiota. However, the heterogeneity of the protocols used and the short time duration of the experiments lead to results that are difficult to compare and draw conclusions at the slaughter-age of broilers. Nevertheless, the combined approach using complementary in vitro and in vivo tools (cell cultures and animal experiments) leads to a better characterization of probiotic strains and could be employed to assess reduced Campylobacter spp. colonization in chickens if some parameters are optimized.

Antimicrobial and antifungal activities of Lactobacillus curvatus strain isolated from homemade Azerbaijani cheese.

The aims of this study were to characterize inhibitory activity spectra, some probiotic properties and safety of Lactobacillus curvatus A61 for its future application in production of fermented foods. The studied strain was isolated from traditional homemade cheese manufactured in Azerbaijan. The cell-free supernatant of culture of Lb. curvatus A61 inhibited the growth of tested LAB, as well as of Listeria monocytogenes and Bacillus cereus strains. The strain presented antifungal activity and inhibited the growth of Cladosporium and Fusarium ssp. during co-cultivation on agar media. PCR amplification with specific primers revealed the presence of curvacin A encoding gene in Lb. curvatus A61. Bacteriocin produced by the studied strain was heat stable and active in a broad pH range, and in the presence of Triton X-20, Triton X-80, Triton X-100, ß-mercaptoethanol, Na-EDTA, SDS and NaCl. The mode of action of bacteriocin against selected indicator strains was found to be bacteriostatic. Lb. curvatus A61 was resistant to physiological concentrations of bile salts and showed high auto-aggregation ability, as well as co-aggregation ability with pathogenic L. monocytogenes strains. It was sensitive to chloramphenicol, penicillin, tetracycline, ciprofloxacin and vancomycin, but resistant to ampicillin and gentamicin.

Purification and characterization of a new bacteriocin active against Campylobacter produced by Lactobacillus salivarius SMXD51.

Strain SMXD51, isolated from chicken ceca and identified as Lactobacillus salivarius, produced a component that inhibits the growth of Gram-positive and Gram-negative bacteria and especially Campylobacter jejuni. The active peptide from the cell-free supernatant of Lb. salivarius SMXD51 was purified in three steps: (i) precipitation with 80% saturated ammonium sulfate, (ii) elution on a reversed phase SPE UPTI-CLEAN cartridge using different concentrations of acetonitrile, (iii) final purification by reversed phase HPLC on a C(18) column. The mode of action of this peptide of 5383.2 Da was identified as bactericidal, and its amino acid composition was established. This new bacteriocin SMXD51 appears potentially very useful to reduce Campylobacter in poultry prior to processing.

Genome sequence of Lactobacillus salivarius SMXD51, a potential probiotic strain isolated from chicken cecum, showing anti-campylobacter activity.

We report the draft genome sequence of Lactobacillus salivarius SMXD51, isolated from the cecum of healthy chickens showing an activity against Campylobacter--the food-borne pathogen that is the most common cause of gastroenteritis in the European Union (EU)--and potentially interesting features for a probiotic strain, explaining our interest in it.

Identification of lactobacilli residing in chicken ceca with antagonism against Campylobacter.

Bacteriocins produced by Lactobacillus salivarius have been recently recognized as a natural means to control Campylobacter and Salmonella in live poultry. This finding is of relevance since Campylobacter jejuni and Campylobacter coli are the predominant species isolated from poultry that are associated with human campylobacteriosis. In the present work, lactic acid bacteria (LAB) isolated from the cecum of twenty Tunisian chickens were identified and those isolates with antagonism against Campylobacter were further characterized. Following their preliminary confirmation as LAB, 150 strains were identified by combining morphological criteria, biochemical tests, and molecular methods, the latter inluding intergenic 16S- 23S PCR, specific lactobacilli PCR, and a biphasic approach. Most of the LAB isolated belonged to the genus Lactobacillus, among them Lb. sakei (33.3%), Lb. salivarius (19.4%), Lb. reuteri (8.6%), and Lb. curvatus (8.6%). The other LAB strains included those of the genus Weissella (16.7%), Enterococcus faecalis (5.3%), Leuconostoc mesenteroides (2.7%), Lactococcus graviae (2.7%), and Streptococcus sp. (2.7%). The Lactobacilli strains were tested for their antagonism against C. jejuni and C. coli. The activity of three of them, Lb. salivarius SMXD51, Lb. salivarius MMS122, and Lb. salivarius MMS151, against the aforementioned target strains could be ascribed to the production of bacteriocins.

Identification of lactobacilli residing in chicken ceca with antagonism against Campylobacter

Bacteriocins produced by Lactobacillus salivarius have been recently recognized as a natural means to control Campylobacter and Salmonella in live poultry. This finding is of relevance since Campylobacter jejuni and Campylobacter coli are the predominant species isolated from poultry that are associated with human campylobacteriosis. In the present work, lactic acid bacteria (LAB) isolated from the cecum of twenty Tunisian chickens were identified and those isolates with antagonism against Campylobacter were further characterized. Following their preliminary confirmation as LAB, 150 strains were identified by combining morphological criteria, biochemical tests, and molecular methods, the latter inluding intergenic 16S- 23S PCR, specific lactobacilli PCR, and a biphasic approach. Most of the LAB isolated belonged to the genus Lactobacillus, among them Lb. sakei (33.3%), Lb. salivarius (19.4%), Lb. reuteri (8.6%), and Lb. curvatus (8.6%). The other LAB strains included those of the genus Weissella (16.7%), Enterococcus faecalis (5.3%), Leuconostoc mesenteroides (2.7%), Lactococcus graviae (2.7%), and Streptococcus sp. (2.7%). The Lactobacilli strains were tested for their antagonism against C. jejuni and C. coli. The activity of three of them, Lb. salivarius SMXD51, Lb. salivarius MMS122, and Lb. salivarius MMS151, against the aforementioned target strains could be ascribed to the production of bacteriocins (AU)

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