Accumulation of Iron in Lactic Acid Bacteria and Bifidobacteria

Abstract

ABSTRACT Lactobacillus acidophilus, L. delbrueckii var. bulgaricus, L. plantarum and Streptococcus thermophilum , all used extensively in the food industry, were tested for their ability to internalize and/or oxidize ferrous iron (Fe 2 +). For comparison some experiments were performed with bifidobacteria, B. thermophilum and B. breve . All organisms except L. bulgaricus could transport Fe 2+ into the cell, where it was partially oxidized to the ferric form (Fe(III)). In addition, L. acidophilus and L. bulgaricus could oxidize Fe 2+ to Fe(III) extracellularly through the elaboration of H 2 O 2 into the medium when the experiments were carried out in air. L. bulgaricus elaborated H 2 O 2 only in the presence of glucose, whereas L. acidophilus released H 2 O 2 in absence of glucose. We concluded that lactic acid bacteria, like bifidobacteria, can exert some beneficial effects in animal organisms, or in food processing and storage, by making Fe 2+ unavailable to harmful microorganisms.