Background:
Microorganisms commonly employed in food industry, such as Lactobacillus plantarum and
Saccharomyces cerevisiae, are also excellent natural nanotechnologists. They reduce selenite (SeO3
2-
) to form
nanoparticles of red selenium (Se0
) of exceptional quality and with interesting physical and (bio-)chemical properties.
Objectives:
The production of these nanoparticles has been studied in several relevant microorganisms to gain a better
picture of the overall properties and quality of these particles, possible differences between producers, ease of production
and, in particular, biological activity.
Methods:
Several common microorganisms, namely L. plantarum, S. cerevisiae and Escherichia coli have been cultured
under standard conditions and 1mM concentrations of SeO3
2- have been converted to red particles of elemental selenium.
These particles have been characterized extensively with respect to uniformity, size, shape, consistency and, in particular,
biological activity against infectious microbes.
Results:
Highly uniform amorphous spherical particles of 100 nm to 200 nm in diameter could be produced by several
microorganisms, including Lactobacillus. Although originating in bacteria and yeast, these particles exhibit antimicrobial
activity when employed at concentrations of around 100 µM. This activity may in part be due to the inherent chemistry of
selenium and /or of the protein coating of the particles. Interestingly, yeast also forms larger rod-like structures. These
micro-needles with around 85 nm in diameter and up to 3 µm in length exhibit considerable antibacterial activity, possibly
resulting from additional, physical interactions with cellular structures.
Conclusion:
Common microorganisms traditionally employed in the preparation of food produce nanoparticles of
selenium which may be harvested and explored as natural antimicrobial agents or antioxidants. These particles provide a
fine example of and lead for natural nanotechnology with biological activity and applications in food and food
supplementation, medicine, agriculture and cosmetics.
Completing the ENCODE3 compendium yields accurate imputations across a variety of assays and human biosamples
