Ferrous iron oxidation by Lactobacillus acidophilus and its metabolic products

Abstract

Lactobacillus acidophilus (ATCC 43561, grown in trypticase-phytone-yeast extract medium under anaerobic conditions, was capable of accumulating nanomolar quantities of iron when presented with Fe2+ at pH 6.5. A major factor in the ability of the organism to accumulate iron was its ability to produce and export H202, which oxidized Fe2+ to Fe(II1). The latter was bound to the cell surface by a trypsin-sensitive protein. H202 production was inhibited by low pop and glucose. L . acidophilus contained an Fe2+ transport mechanism and an intracellular heat-sensitive ferroxidase comparable to that of bifidobacteria. Lactate produced by the organism facilitated Fe2+ oxidation by 0 2 , but the Fe(II1) produced remained sequestered by the lactate. It was concluded that L . acidophilus may participate in the nutritional immunity scheme under certain circumstances.

Iron requirement of Lactobacillus spp. in completely chemically defined growth media

“…acidophilus . The oxidation of Fe 2+ to Fe 3+ in lactobacilli involves hydrogen peroxide produced by bacterial cells during aerobic incubation; this generates Fe(OH) 3 which binds the bacterial cell ( Kot et al . 1995b, 1996, 1997).…”

Differential Effects of Transition Metals on Growth and Metal Uptake for Two DistinctLactobacillusSpecies

“…Previous work recorded either very little iron uptake in the same strain of L. plantarum or some Fe 2+ accumulation in both species, but the growth conditions were different than those in this current study ( 21 , 24 , 50 ). Specifically, this work varies from previous studies in composition of growth media, the growth phase at which samples were collected, whether bacteria were incubated in anaerobic or aerobic conditions, which could lead to different CO 2 metabolism ( 108 , 109 ), and in carbon source or presence of glucose ( 110 – 112 ).…”

Binding of Fe(OH)3toLactobacillus delbrueckiissp.bulgaricusandLactobacillus acidophilus: Apparent Role of Hydrogen Peroxide and Free Radicals

“…Heated cells were not able to produce lactic acid or H 2 O 2 . It is noteworthy that ferrous iron uptake by lactobacilli (and bifidobacteria) is abolished following heating of cells (Kot et al, 1995); binding of Fe(OH) 3 by heated cells, on the other hand, is augmented following heating.…”

“…Binding of ferric hydroxide by both organisms was concentration-dependent, and binding could be largely abolished by treating these cells with trypsin (Kot et al, 1995(Kot et al, , 1996. In addition, binding was temperaturedependent.…”

“…bulgaricus (L. bulgaricus). It was found that both organisms were able to oxidize ferrous iron to the insoluble and less available ferric form via an elaboration of hydrogen peroxide and that the resulting Fe(OH) 3 could become firmly bound to the bacteria (Kot et al, 1995(Kot et al, , 1996.…”