Reduced Campylobacter jejuni colonization in poultry gut with bioactive phenolics

Abstract

This study was designed to determine the effects of bioactive phenolics (BPE) extracted from blackberry (Rubus fruticosus) and blueberry (Vaccinium corymbosum) byproducts/pomaces on Campylobacter jejuni colonization in broiler cecum. We raised a total of 120 Cobb-500 broiler chicks in duplicate trials up to 3 weeks to determine the effect of BPE on the reduction of colonization using a C. jejuni RM1221 marker strain in broiler cecum. We observed that, as a water supplement, 1.0 g Gallic Acid Equivalent (GAE)/L of BPE reduced C. jejuni colonization level by 1 log in three weeks old broiler cecum compared to the control group. 1 g GAE/L of BPE also resulted a complete inhibition of the C. jejuni marker strain in drinking water with a potential for reduced horizontal transfer in poultry flocks. In a separate experiment, we also raised a total of 200 Cobb-500 broilers in duplicate trials up to 6 weeks to investigate natural colonization of Campylobacter in presence of BPE and observed that 1.0 g GAE/L of BPE reduced natural colonization level of Campylobacter by 2 logs in broiler cecum as a water supplement. Relative expression of several C. jejuni stress response genes, including rod shape determining protein (mreB) were down-regulated in the presence of sub-lethal concentration of BPE. Prolonged exposure of C. jejuni to BPE resulted the minimum inhibitory concentration (MIC) of BPE to increase from 0.5 to 1.0 mg GAE/mL; however, after single sub-culture in BPE-free broth, the MIC value revived to 0.5 mg GAE/mL. Findings from this study reveal the high potential of berry phenolics as green antimicrobials against enteric pathogen Campylobacter and application in the reduction of pre-harvest colonization level of Campylobacter in poultry gut.