Bioformation of Selenium Nanoparticles During the Cultivation of Bifidobacteria

There are numerous studies on the biotechnological (‘green’) synthesis of nanoparticles of gold, silver, selenium, platinum and other compounds by bacteria, actinomycetes, fungi and yeasts, since the search for effective biological nanoparticle producers is currently underway. Nevertheless, little information is devoted to the production of selenium nanoparticles (SeNP) with the use of probiotic microorganisms. Thus, the aim of this work is to study the bioformation of selenium nanoparticles using strain 83 of Bifidobacterium bifidum. The size and amount of selenium nanoparticles in the culture medium are studied by the laser diffraction method employing the SALD-7500 Laser Diffraction Particle Size Analyzer. As a result, a ‘green’ biotechnological method for the synthesis of selenium nanoparticles during the cultivation of bifidobacteria is developed. Bifidobacteria are shown to be resistant to the high selenium concentrations and transform toxic sodium selenite Se(IV) into non-toxic elemental Se(0) of zero-valence with sizes ranging from 20 to 45 nm. The method described in the present work gives the opportunity to obtain nanoparticles of small size compared to previously reported studies. The high stability, homogeneity and small size of selenium nanoparticles make them promising for use in medicine and food industry. The results of the present work include the optimal parameters of cultivation of Bifidobacterium bifidum strain 83: the optimum concentration of sodium selenite 2 mg/ml, inoculum dose 5%, cultivation time 24 h and cultivation temperature 37 ºC. Bioformation of selenium nanoparticles with the use of bifidobacteria is particularly relevant in connection with the simplicity, availability and environmental safety of this method. The method gives new perspectives for the development of biologically active additives, which contain non-toxic selenium.