Probiotic potential of Lactobacillus isolates of chicken origin with anti-Campylobacter activity

Abstract

Campylobacteriosis is currently the most frequent zoonosis in humans and the main source of infection is contaminated poultry meat. As chickens are a natural host for Campylobacter species, one strategy to prevent infection in humans is to eliminate these bacteria on poultry farms. A study was conducted to evaluate the probiotic potential of 46 Lactobacillus isolates from chickens faeces or cloacae. All lactobacilli were able to produce active compounds on solid media with antagonistic properties against C. jejuni and C. coli, with L. salivarius and L. reuteri exhibiting particularly strong antagonism. The cell-free culture supernatants had a much weaker inhibitory effect on the growth of Campylobacter, and the neutralization of organic acids caused them to completely lose their inhibitory properties. The ability to produce H₂O₂ was exhibited by 93% of isolates; most of isolates had a hydrophobic surface, showed excellent survival at pH 2.0 or 1.5, and displayed tolerance to bile; 50% isolates displayed the ability to biofilm formation. Determination of MICs of various antibiotics showed that as much as 80.4% of Lactobacillus isolates were resistant to at least one antimicrobial agent. Seven ultimately selected isolates that met all the basic criteria for probiotics may have potential application in reducing Camylobacter spp. in chickens and thus prevent infections in both birds and humans.

Keywords: Campylobacter; Lactobacillus; antibacterial activity; chicken; probiotics.

Fig. 1.

Agarose gel (2%) showing the amplicon patterns obtained in multiplex PCR for reference and wild isolates (7, 15, 27, 41) of C. jejuni and C. coli; profiles contained the following amplicons: 16S rDNA 860 bp, mapA 590 bp, ceuE 460 bp.

Fig. 2.

Effect of isolates of various Lactobacillus species on the growth of indicator bacteria, as determined by the agar slab method. Different capital letters (A–G) indicate significant differences (P<0.05) between mean diameters of growth inhibition zones caused by individual Lactobacillus species; vertical bars denote 0.95 CI.