SELENIUM AND LACTOBACILLUS SPECIES

Selenium(Se) is an essential element for man and animal. Supplementati on of Se has been done with Se-enriched yeast and inorganic Se compoun ds. In the present study a quantitative and qualitative evaluation was made of whether lactobacilli are able to concentrate Se. A high corre lation was found between the bacterial Se concentration and the concen tration of Se in the medium. The Se concentration in biomass was respe ctively 253 +/- 50, 375 +/- 33 and 407 +/- 108 mu g g(-1) dry weight f or Lactobacillus delbrueckii subsp. bulgaricus, Lact. plantarum and La ct. casei subsp. casei when 1 mg 1(-1) Se4+ was present in the medium. Manganese (Mn) was concentrated in Lact. plantarum and Lact. casei su bsp. casei but not in Lact. delbrueckii subsp. bulgaricus. The Mn conc entration in biomass was higher compared to the Se concentration but t his difference decreased when the concentration of Mn/Se increased in the culture medium. Copper, zinc and iron were also concentrated in bi omass of Lact. delbrueckii subsp. bulgaricus. Characterization of the bacterial selenocompound revealed that Se-75 was generally incorporate d, as selenocysteine, into protein of Lact. delbrueckii subsp. bulgari cus. Addition of L-cysteine to the medium decreased the bacterial Se c ontent. It was concluded that Lact. delbrueckii subsp. bulgaricus inco rporated Se non-specifically into bacterial protein. The application o f Se-enriched lactobacilli (Se-Lb) in Se supplementation would be an i nteresting approach since selenomethionine, which is the major selenoc ompound in commercialized Se-yeast, was not detected in Se-Lb and beca use lactobacilli are already widely used in human nutrition.