Purpose: The purpose of this study was to investigate the phenotypic and genotypic alterations of C. jejuni exposed to both lethal and sub-lethal concentrations of berry phenolic extracts.
Methods: Bacterial growth pattern, cell surface hydrophobicity, auto-aggregation capability were determined. Adhesion and invasiveness assay was carried out in cell-culture model. Expression of virulence genes was determined with qRT-PCR. In vivo experiment was carried out in a-day-old chick model.
Results: Minimum bactericidal concentration of blackberry and blueberry pomace extracts (BPE) were 0.8 and 0.6 mg GAE/ml on C. jejuni. Treatment with sub-lethal concentrations of BPE altered the cell surface hydrophobicity, auto-aggregation capacity, and cellular motility, significantly. Interaction of C. jejuni with cultured host cells were altered significantly; BPE reduced bacterial invasion into human intestinal epithelial cells (INT407) and in chicken fibroblast cells (DF1) by > 0.5 logs, compared to the control. Differential expression of perR, flvA, sodB, fdxA, cmeB, cmeC, and clpA genes in C. jejuni were observed, due to treatment with BPE. In chicken model, 1.0 mg GAE/ml BPE as water supplement reduced the natural colonization of Campylobacter in chicken cecum by > 5 logs compared to the control group.
Significance: This study shows that bioactive extracts from berry pomace can serve as a potential alternative to synthetic antimicrobials and reduce Campylobacter colonization in farm animals specifically poultry, to improve product safety.