Selenite tolerance and accumulation in the Lactobacillus species

The effect of selenium as selenite (Se4+) on cell growth and accumulation in the Lactobacillus species was investigated in batch cultures using Se4+ supplemented MRS broth. All the strains, except two, Lactobacillus rhamnosus LB3 and Lactobacillus fermentum LB7, for which a functional role of Se can be suggested, were inhibited by 1 mg l(-1) of Se4+. Six tested Lactobacillus strains were able to concentrate selenium, though in different amounts. Most was membrane-bound, and was, in part, bound to -SH groups on the external membrane surface. Selenium was also accumulated in the cytoplasm in both the organic and the elemental form. The isolates were characterised by biochemical reactions and 16S rDNA restriction enzyme profiles and different species of Lactobacillus were assigned on the basis of 16S rDNA sequences.