Influence of Zinc Sulphate on the Probiotic Properties of Lactobacillus plantarum CCM 7102

The effects of zinc sulphate on selected properties of L. plantarum CCM 7102 were tested in vitro. The resistance of lactobacilli to higher concentrations of ZnSO₄ (up to 5000 mg Zn²⁺.l⁻¹) in growth media was strain-dependent. Further studies were carried out on the most resistant strain of L. plantarum CCM 7102. While the addition of low concentrations of zinc sulphate into the growth media (< 100 mg Zn²⁺.l⁻¹) did not influence the properties of L. plantarum CCM 7102, the concentrations of 100—500 mg Zn²⁺.l⁻¹ stimulated: the growth rate, production of lactic acid, adhesion to porcine enterocytes and the inhibition of pathogens E. coli O8:K88⁺ent⁺, S. enterica and S. Typhimurium. Conversely, however, high concentrations > 500 mg Zn²⁺.l⁻¹ inhibited these properties. The addition of zinc (250 mg Zn²⁺.l⁻¹) did not affect the resistance to antimicrobials, low pH, and the resistance to bile salt was affected only weakly. Zinc-resistant probiotic Lactobacillus strains are suitable for use in feedstuffs with a higher content of zinc designed for the prevention of post weaning diarrhoea in pigs.