Purpose: Examine the impact of vitamin exposure on adherence of Escherichia coli O157:H7 to HeLa cells.
Methods: Three independent E. coli O157:H7 cultures were exposed to optimized concentrations of enterically produced (biotin, folate, riboflavin, menaquinone, pantothenate and cobalamin) or food-related vitamins (ascorbate, α-tocopherol). At 1.5 and 3h, cells were plated on Luria Bertani agar or screened for adherence/invasive capacity using HeLa cells, and compared to respective controls.
Results: Following vitamin exposure, significantly fewer bacteria were observed in pantothenate (50 mg/ml, 1.5 and 3h; P < 0.001) and ascorbate [10 mg/ml, 1.5 (P < 0.05) and 3h (P < 0.001)] treatments, while significantly more E. coli O157:H7 were observed in biotin (0.1 mg/ml, 1.5h; P < 0.05) and cobalamin (1 mg/ml, 3h; P < 0.05) treatments when compared to controls. Following 1.5h exposure, significantly increased adherence to HeLa cells was observed for ascorbate (0.1 mg/ml; P < 0.05), pantothenate (5 mg/ml, 50 mg/ml; P < 0.001) and cobalamin (0.01, 0.1, 1 mg/ml; P < 0.001) treatments whilst exposure to folate (0.001 mg/ml; P < 0.001) and biotin (0.1 mg/ml; P < 0.05) reduced adherence. At 3h exposure, significantly increased adherence was observed for biotin (0.01, 0.1mg/ml; P < 0.05), riboflavin (0.0001, 0.001, 0.01 mg/ml; P < 0.001, P < 0.01, P < 0.001, respectively), pantothenate (5, 50 mg/ml; P < 0.001), cobalamin (0.01, 0.1, 1 mg/ml; P < 0.001) and α-tocopherol (1 mg/ml; P < 0.001).
Significance: Our results show vitamins may influence the adherence capacity of E. coli O157:H7 to HeLa cells, suggesting a possible role as an environmental cue in the intestinal environment. As such, further work is required to quantify the manner by which vitamins associated with us or our food influence stress and virulence processes in E. coli O157:H7.