Bacteriocins reduceCampylobacter jejunicolonization while bacteria producing bacteriocins are ineffective

Abstract

Broiler chickens are widely considered an important source of human exposure to Campylobacter jejuni because of the high numbers found colonizing the chicken gut and the consequent contamination of processed carcasses.We hoped to intervene in C. jejuni gut colonization by using a defined probiotic. Chicken intestinal contents were screened for diverse bacterial isolates that manifested C. jejuni inhibition. These antagonistic bacteria were fed directly to chickens before or after C. jejuni challenge. The prophylactic probiotic treatments were effective only when very low challenge levels of C. jejuni were used. Otherwise, probiotic treatments failed to reduce C. jejuni colonization. Regardless of treatment, as birds further aged C. jejuni numbers soon approached the levels observed in the control birds. We sought an alternative approach, as commercial broilers may be exposed to infectious levels of C. jejuni at any time during production. Two of our most promising antagonistic isolates, Lactobacillus salivarius NRRL B-30514 and Paenibacillus polymyxa NRRL B-30509, were further studied for effectiveness in reducing C. jejuni in chickens. When 250 mg of purified bacteriocins (produced by these organisms)/kg feed were fed therapeutically to chickens colonized with C. jejuni, colonization was reduced by at least one million-fold. Treatments with viable probiotic bacterial cultures were ineffective in reducing C. jejun i in chickens, while bacteriocin treatment from these corresponding bacteria substantially reduced C. jejuni colonization in the live birds. Key words: bacteriocin, Campylobacter jejuni, colonization, probiotic, broiler chicken, competitive exclusion, Lactobacillus salivarius, Paenibacillus polymyxa